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In the mid 21st Century a dinosaur fossil dig team has encountered something a little different from what they are used to. They have stumbled upon some kind of unknown ooze or slime, preserved in amber. Since they are unsure of what they have found, they'd presumably pass it on for further study in a lab somewhere. What they don't know yet is that this slime contains microbes of extra-solar origin(meaning not from within our solar system). If the truth came out it would be no doubt be the find of the century, maybe even the millennium.

My question is this: is it at all plausible that the alien origin of the microbes somehow avoids detection, even under close scrutiny by scientists?

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    $\begingroup$ @NomadMaker: For the purposes of the question, the age of the organism is likely not relevant here. If two aliens have a baby on Earth, that baby is still an alien. There's no requirement for the specific organism in the amber having to predate the planet itself - even if its (alien) species is older. $\endgroup$ – Flater Apr 30 at 10:43
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    $\begingroup$ What, you mean dolphins arn't an alien species sent to observe us? $\endgroup$ – CGCampbell Apr 30 at 12:58
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    $\begingroup$ Note carbon dating is not effective for dates in excess of 50,000 years, although a range of other techniques are available for older samples. $\endgroup$ – Slarty Apr 30 at 14:03
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    $\begingroup$ @NomadMaker The very youngest Amber is about 16 million years old. C14 dating is useless past 50000 years. Thus, no amber dating using C14 method will deliver any result whatsoever. $\endgroup$ – PcMan Apr 30 at 17:07
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    $\begingroup$ @CGCampbell I mean, if for no other reason than sending a strictly aquatic species to observe a mostly land-based one would be a pretty poorly planned invasion strategy... $\endgroup$ – Darrel Hoffman Apr 30 at 17:21
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So, as a paleontologist, I can tell you that the paleontologists at your site probably wouldn't even collect the amber in the first place. Fossil sites produce a lot of pieces of small, fossilized junk like small chunks of bone or carbonized wood that don't get collected. In a site where you have a lot of things preserved as "items" such as breaking open concretions or as nodes of amber, it's very common to just throw out anything that doesn't have a clear fossil in it. Storage space is limited in most natural history museums and (I've seen paleontologists even admit to not collecting entire well-preserved skeletons of oreodonts or skulls of Triceratops simply because these animals are so common in their respective formations, which has been criticized by other researchers as biasing the fossil record).

Even when stuff is collected, it's very common for specimens to languish for decades, or even centuries. Some of the material I have been working on are species of flashy carnivorous megafauna that are totally new to science, but they were collected nearly a century ago and were gathering dust in the collections unstudied until then. If those kinds of animals can be overlooked for being uninteresting, imagine how easily a blob of slime could be. There is just so much material in museum collections that has never been looked at, and a piece of amber containing indeterminate slime would be so far at the bottom of a researcher's priorities, even if it did turn out to be evidence of alien life, because it doesn't look interesting at first glance.

As an example, consider this. This is a press release from a study describing a slime mold (Mycetozoa) from amber in northern Myanmar. They didn't notice the fossilized slime mold was there until they put the specimen under detailed inspection, and the only reason anyone even noticed it was there was because it had gotten attached to the foot of a lizard, which are super rare in amber-producing beds and hence researchers tend to collect every vertebrate preserved in amber they can find. If that lizard wasn't there the slime mold would have either languished in a museum collection for centuries or, more likely, it would have never been picked up and would have been sold off to make jewelry.

Or, to use another example, one of the specimens in this recent study on dire wolves was an almost unidentifiable tooth fragment collected back in...1989 or so. No one knew it was a dire wolf (they thought it might be a bear but they weren't sure), and they only collected it out of a sense of completeness. It was only discovered the tooth was dire wolf when they decided to DNA test it.

Even if people did notice something was off about it, they would probably catalog it as weird Earth life rather than alien. NASA claimed that they found a lifeform that used arsenic, and while their claim turned out to be untrue it's worth noting that they framed it as "weird extremophile Earth-life" rather than alien. The only way an alien would be noticed is if it had radically different biochemistry from Earth life, like not even storing its biological information in nucleic acids.

Edit: Something else that occurred to me reading some of the other answers is that even if the life form was alien, and even if the amber did get collected, the organic material the alien was made of would have likely decayed beyond the ability of science to detect. DNA has a half-life of 521 years, and the oldest DNA is from the Pleistocene. Even if the alien had a non-terrestrial genetic code, it would likely have decayed into unidentifiable organic compounds in the 66 million years since it was preserved. Some people have claimed to find preserved collagen and red blood cells in Cretaceous dinosaur fossils, but this is highly controversial because this has only ever been found by a single research group whose results cannot be replicated by any other lab. And as an aside, this is what most people would probably think of your alien: it's not true extraterrestrial life, it's some recent organic contaminant of the amber. Any evidence of alien-ness would have to be so radically different from Earth life there is no way it could decay into unrecognizability.

tl;dr: It's very likely that no one would ever notice it, but it's also likely the specimen wouldn't have been collected in the first place or considered not interesting by future researchers.

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    $\begingroup$ I agree unless the stuff looks looks unusual the chances of it being collected are low. Although it has a better chance in amber today as pollen studies are becoming more and more common. If it is examined in detail it will be by someone interested in micro organisms, pollen, or amber chemistry. So it is entirely possible it may sit in a bucket or box for years or decades without anyone doing anything to it. the further back in history it was collected the less chance anyone has actually examined it in detail. $\endgroup$ – John Apr 29 at 17:49
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    $\begingroup$ The only way anyone will realize it is extra solar is if someone does a very detailed study chemical analysis on it and it doesn't use any earth nucleotides. Even then they may be more likely to chalk it up to error or diagenesis unless a lot of other stuff is off. $\endgroup$ – John Apr 29 at 17:52
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    $\begingroup$ "I've seen paleontologists even admit to not collecting entire well-preserved skeletons of oreodonts or skulls of Triceratops simply because these animals are so common" - Huh. So they just leave them in the ground? I wonder what the market price is for a well preserved Triceratops skull is then... [looks it up] $125,000? Huh. $\endgroup$ – user56reinstatemonica8 Apr 30 at 7:23
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    $\begingroup$ @user56reinstatemonica8 Yep. In some cases I've seen them actually throw out Tyrannosaurus rex specimens because of legalese. They're also massively hypocritical about it, most paleontologists in North America have a hard-line stance against private ownership or collection of vertebrate specimens even on private land (it's a complex issue with points on both sides that can't be easily explained in a comment, there are good reasons against it), but then they leave important fossils in the ground to erode and most of them have private vertebrate fossil collections of their own. $\endgroup$ – user2352714 Apr 30 at 19:21
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    $\begingroup$ @user56reinstatemonica8 I've even seen issues where paleontologists in Florida destroyed a nearly complete skeleton of a gomphothere because they only wanted to salvage the pelvis and femur for a research project, and destroyed the forelimbs and torso. Paleontology, especially in the U.S. and Canada is massively corrupt and has a huge elitist, anti-citizen scientist attitude and a severe lack of an ability to self-reflect or compromise out of pragmatism. Most want to die on the ideological hill that they've chosen. $\endgroup$ – user2352714 Apr 30 at 19:23
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I have a confession to make, which when it prefaces my answer, will make some sense to you. I like fringe science theories. Mind you, I don't necessarily believe them (I struggle to think of any that are plausible), but they help me to understand the border between plausibility and implausibility.

One such theory that I read about years ago posited a sort of single-celled life on earth, the diameters of which fall below the minimums for single-celled organisms. At the time there were one or two popular articles on it, rainwater had been falling someplace and was discolored (red I think?). Some fringer suddenly appeared and was claiming that when observed under a microscope, small red particles were observed and were a novel kind of life. The particles were maybe 50nm in size (this is more of a guess than a memory).

No previously discovered single-celled organisms have been discovered that were so small, and to date none have been. Imaging these things would be difficult to determine if they were indeed alive, and more importantly, it seemed impossible to culture them. That last one's important, it's impossible to culture most singled-celled organisms successfully (and yet we're certain they're alive).

The fringers like latch on to things like that. To find little places to with enough wiggle room that what they claim isn't impossible. And indeed, it's not impossible that this was an incident involving a novel life form. The minimum size of a cell is indeed set at 150-200nm because knowing what we know of life, there is some minimum equipment necessary for one to be alive and be able to reproduce, and it doesn't seem to fit in less space than that.

But if it wasn't using the normal equipment, all bets are off. It could use another molecule to encode genes. It could use different amino acids, different base pairs, different codons... codons that use more than or fewer than the triplets of base pairs. These could use left-handed vs. right-handed amino acids. They might not have ribosomes like we have (the little robots that take a strand of RNA and use it to build a specific protein).

And, not only might this reduce the size of the cell (some of them anyway), it would make it nearly undetectable to some of the very processes and equipment we use to detect life. Especially if no one is looking for those specific things.

Such an organism could slip under our radar, and might be doing so even now. And as far as life goes, we aren't even yet discussing anything especially exotic. If life can exist in what we consider hostile environments, than anything in the deep crust or upper mantle is completely invisible to us (currently). There could exist another wholly independent tree of life in the deep oceans. Or the upper atmosphere. If these things are microscopic and are not antagonistic to our tree of life, then they might even be living in that dust bunny on the desk behind your monitor, right now. Slow-growing, always present, small enough biological (if that's even the right word) mass as to go unnoticed.

I have no reason to believe such an organism exists, and more than a few to believe that it does not, but it wouldn't be impossible. We might miss such things, even when looking directly at them. Might not even believe them to be alive.

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    $\begingroup$ I remember I read the same news some years ago. I think the red rain you are talking about happened in India $\endgroup$ – McTroopers Apr 29 at 19:44
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    $\begingroup$ Fringe science is of course perfect fodder for science fiction and worldbuilding, if a whole group of crackpots (usually highly intelligent and determined) has already collected alternative theories that looks kinda plausible on the surface if you squint. $\endgroup$ – pipe Apr 30 at 21:03
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Depends on the organism

Most likely it'll not be seen as alien. It can be assumed that the microbes have more or less the same biological structure that any living organisms has on Earth. The microbes discovered are likely to fall close to one or more microbe family on Earth, so they would be classified as a similar family. If it falls completely outside any existing microbial family, it'll likely be classified as a new species. If that happens they try to make a convincing way that they must have evolved, but the amount of effort for that can be minimal.

The idea it is of extraterrestrial origin is outlandish, as we already have so much life here. Much of which we don't know or understand yet. New insects are still classified nearly every day. Microbes are much more in number and species. Even under the greatest suspicion it is extraterrestrial, Occams razor tells that the easier explanation is that it originates from Earth and we just hadn't seen it yet.

The only way that it would grant real suspicion is if it is found on extraterrestrial material (asteroids) or has truly biological signs, like no DNA or using processes for metabolism that don't exist on Earth.

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  • $\begingroup$ "It can be assumed that the microbes have more or less the same biological structure that any living organisms has on Earth". I don't think it can. We only have one example of biogenesis to go on another example might well be very different. We simply don't know. $\endgroup$ – Slarty Apr 30 at 14:09
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Aliens can be Whatever

The thing about aliens is that we, as humans, have absolutley NO IDEA what any of them would look like, act like, or how they would even work. Earth has very specific abiotic parts that make life as we know it possible, but alien life could be different.

The alien world in which it origionated could have an atmosphere very different. Most of the noble gasses or other non or low-reactive gasses could make up the atmopshere, similar to Earth's nitrogen atmosphere, but different. Maybe even a neon atmosphere. There also could be little to no water, and the chemical reactions the animals do to survive could be completely different compared to humans and the creatures there. We would have no way of knowing if aliens would be completely different.

The alien microbes could look similar to human or animals cells, or they could be so small humans cant see them. They could also be so out there that scientist don't even know that it's alive, or was at some point. If you were to make the microbes evolve in an enviroment that is completely different compared to Earth, you can really do a large amount of things to hide them. As for the way they got here, it could be an astroid that crashed hundreds of millions of years ago. The microbe could of hitched a ride, gotten off the asteriod by whatever way the microbes move, or gotten picked up by an animal, then getting trapped in the sap.

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    $\begingroup$ "The thing about aliens is that we, as humans, have absolutley NO IDEA what any of them would look like, act like, or how they would even work." We do have an idea. Unless our understanding of even the most fundamental laws of physics and chemistry is seriously wrong. For example life needs an energy source, there are upper and lower limits on size, temperature etc. $\endgroup$ – Michael Apr 30 at 8:39
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It’s not only plausible, it’s actually extremely likely.

First off, let’s assume that the sample was actually collected (effectively ignoring the excellent points raised in the answer by user2352714, as there’s not much point otherwise), and it was noticed that there was something anomalous about it (which even ignoring the points raised in the aforementioned answer is still statistically unlikely if the anomaly is microbial in nature).

At this point, the next most important factor is that we know absolutely nothing about how likely alternative biochemistries are. We quite simply cannot rule out that our current data on biochemistry is subject to the weak anthropic principle. More concretely, we have no way to know for certain that alternative biochemistries cannot exist (we haven’t even ruled out whether they exist on Earth or not, though notably pure statistical simulation would suggest that if they can exist, they probably do somewhere (though not necessarily on modern Earth)).

If alternative biochemistries do not exist (or the microbe happens to have a very ‘Earth-like’ biochemistry)

It is very likely that this microbe will be misidentified as being terrestrial in origin. We’ve catalogued only a tiny fraction of all microbe species on Earth, ‘new’ ones crop up with some regularity. amd from there a simple application of Occam’s Razor would indicate it’s probably terrestrial unless there is a lot of compelling evidence otherwise. This is the same reason that you never see mainstream astronomers claiming extrasolar radiation that happens to have a peculiar pattern is a message from an alien, it’s just so much more likely that it’s an equipment malfunction, a distorted and reflected signal from Earth, or even a naturally occurring phenomena that we have yet to identify than happening to be a message from an alien life form (pretty much invariant of how you choose to resolve the Fermi paradox).

If alternative biochemistries do exist and the microbe utilizes one

It may not even be recognized as life. Perhaps what gets found is actually a dormant state (such as the endospore state found in some species within the phylum Firmicutes (such as C. tetani or B. anthraxis). There’s also the possibility that it’s just so different from anything we expect (especially if we still have no knowledge that alternative biochemistries are possible) that we don’t even recognize any metabolic or reproductive processes (consider for example the silicate lifeform encountered in the Star Trek episode ‘The Devil in the Dark’). Far more likely than either case though is that the microbe is simply dead. While we do not know if alternative biochemistries are possible, we do know that they are likely to be very chemically sensitive to their environment if they do exist, just like our own biochemistry is, and it’s unlikely that a microbe with a radically different biochemistry could survive for long in normal conditions on Earth, especially if it’s experienced the conditions required for fossilization of terrestrial life (though I guess this final assertion may be a bit biased).

Even if it is recognized as life though, it will still probably get miscategorized as terrestrial life instead, because it’s well established that there are many highly isolated ecosystems with extremely unique microbes in them.

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    $\begingroup$ "We quite simply cannot rule out that our current data on biochemistry is subject to the weak anthropic principle." To a degree, you can, via Chemistry, since other chemicals either don't work well, or are very rare in the Universe. en.wikipedia.org/wiki/… $\endgroup$ – RonJohn Apr 30 at 3:47
  • $\begingroup$ @RonJohn I’m not necessarily talking about really exotic stuff that would be ruled out by simple factors of chemistry or astrophysics (like the ever popular silicon-based life found in so many sci-fi stories), but more reasonable stuff, like the possibility of a biochemistry based on alternate mixes of chiralities, or a completely different set of amino acids, or even just a novel metabolism. Those can’t be conclusively ruled out, even if they are not visibly present here on Earth. $\endgroup$ – Austin Hemmelgarn Apr 30 at 11:27
  • $\begingroup$ Right, which is why I wrote "to a degree", and did not link to that page's section on alternate chiralities. $\endgroup$ – RonJohn Apr 30 at 12:44
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    $\begingroup$ I agree with this answer and will just add the comment that if you have a sample of slime that you think might contain microbes, the first thing you'll do is use the polymerase chain reaction, which looks for DNA, or a variant of it that looks for RNA. If the alien microbes don't have DNA or RNA then too bad, you won't detect them. You might see them under a microscope, but unless you have a really good reason to investigate further you'll probably assume they're either mineral grains of some sort or the DNA has all decayed. $\endgroup$ – Nathaniel May 1 at 12:23
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Maybe it's already happened

Scientists love finding weird new species. Every year, journals carry news of newly-classified species that were previously unknown to science. For example, below is a photograph of (I'm not making this up) Neopalpa donaldtrumpi, which lives on both sides of the United States-Mexico border.

A moth that looks like Donald Trump

And below are photos of Sciaphila sugimotoi, described here as "A new species of non-photosynthesizing parasitic plant." I'd never heard of a plant like it before writing this answer.

Weird plant discovered recently

OK, now imagine the discovery of something much much weirder than those two examples, like the "ooze or slime" from your question. Scientists would change their theories about life on Earth to accommodate it. What's the difference between these species and alien species? The fact that we discovered them on Earth. That's it. Scientists assume that any lifeform discovered on Earth came from Earth unless they had specific information to suggest that it came from another planet.

EDIT: Clarified last paragraph per comment.

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  • $\begingroup$ There are some very big differences between those an and alien species, for one all of those you have shown use the same amino acids and nucleotides as us. There are plenty of non-photosynthetic parasitic plants. Nothing you have shown is surprising to an actual biologist. $\endgroup$ – John Apr 29 at 17:57
  • $\begingroup$ @John yet if they came from an alien planet, they'd be alien species. The only thing that makes them regular humdrum species is that they came from Earth. $\endgroup$ – Andrew Brēza Apr 29 at 18:02
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    $\begingroup$ No there is thousands of feature they have that identify them as earth life, nucleotides, amino acids, codons, mitochondria, ect, ect. If many of these things were not true alien origin would be a reasonable conclusion. As they sit right now they could be easily determined to be earth origin and they fit very well in to our known models of the evolution of earth life. $\endgroup$ – John Apr 29 at 19:01
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"Alien" is not a biological identifier, it's a geographical one.

My question is this: is it at all plausible that the alien origin of the microbes somehow avoids detection, even under close scrutiny by scientists?

How would one define an organism as alien, if not by knowing that its origin isn't from Earth?

Take the example of jellyfish. Are they alien? But they've been here for ages. So how would we know if they were alien?

It seems you have the cart before the horse here. If something new is found on Earth, without any reason to think it came from elsewhere, why would it be considered alien? This requires specific information on the organism's biology, which in turn also answers your own question.

In other words, it very much depends on what your alien specifically is, and whether it can be proven that it could not have come from Earth. But if it has survived on Earth for all this time, it stands to reason that it is adapted to Earth, and therefore not easily identifiable as being fundamentally different from Earth.

The only way to prove an organism is an alien (without knowing the origin of the specimen in front of you), requires the alien's biology to be incompatible with Earth's biosphere, therefore proving that it could not have evolved on Earth. But if it's incompatible, then it wouldn't be living on Earth, which precludes your specific scenario.


Making it work in a story.

But that doesn't mean that you can't have an extrasolar origin story for this organism. You can connect the organism to its extrasolar origin through inference.

E.g. the organism is perfectly adapted to Earth and no one can spot that it came from elsewhere. But then you find the exact same DNA on an asteroid which you do know (for a fact) came from outside the solar system.

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  • $\begingroup$ It would have to be something with a significantly different biochemistry to indicate a separate biogenesis. For example is didn't use proteins as we know them or used a different range of amino acids or didn't use pentose sugars and DNA or... $\endgroup$ – Slarty Apr 30 at 14:15
  • $\begingroup$ @Slarty: Exactly, but the decision you make there effectively answers the question that is asked here. In order to not notice the alien life, they must not have checked the thing that makes the alien organism stand out from Earth organisms. Also, as an aside, note that you'd require some different biochemistry that is sufficiently compatible for this organism to survive on Earth for whatever amount of time the plot demands. $\endgroup$ – Flater Apr 30 at 14:25
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The short answer is yes it is possible whatever it is. The longer answer is that the likelihood of it being spotted is probably highest if the chemistry is different, but not too different. The range of what is possible using chemistry is vast beyond imagining so it might be useful to consider the spectrum of possibilities:

  1. At one end of the spectrum perhaps the alien life has exactly the same biochemistry as ours. Not very likely perhaps, but it is conceivable if there are very few possibilities that work for life.
  2. Life could be not identical but very similar. For example perhaps it uses the same DNA, but the way each type of protein is coded for is entirely different.
  3. May be it uses different chemical entities for some or all key structures – perhaps the DNA has different bases, different sugars and different amino acids.
  4. The key structures themselves like DNA, fats, proteins and carbohydrates might not exist in the same discrete entities that we know of.
  5. The chemistry may be vastly different using a wide range of very different organic and inorganic substances.
  6. The entity may be energy based and not rely on material substance at all.

Either end of the spectrum seem to be unlikely, but where the balance lies in between is hard to say. But this will have a dramatic effect on how any alien material is classified. 1 would not be seen as alien, 2 might require detailed investigation to reveal its alien origins, 3 should be identifiable as alien from any biochemical analysis, 4 and 5 might not be seen as living at all and could be overlooked entirely unless seen “in action alive” and 6 simply might not be noticed at all.

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If we assume that:

  1. The microbes have nucleic acids
  2. Their genome sequence is not very similar to Earth life
  3. They have reasonable population numbers on Earth and aren't almost extinct

Then it is extremely unlikely in the 21st century, because of advances in genomics that happened in the beginning of the 21st century. Conversely, in the 20th century it's very likely. Even today, scientists are sequencing all sorts of natural samples and eventually your alien microbes would show up in them. All living organisms on Earth share a common evolutionary ancestor and the genome sequences can easily be traced back to their phylogenetic relatives, even if the organism itself is unknown. To me, the premise of an alien organism is that it would have some radically different biology - such biology would make it stick out like a sore thumb in a sequencing study. People would race to publish papers about an apparently biological sequence with no close relative.

If you violate assumption 1, then the microbes could go undetected for a very long time. Biologists will just assume it's non-living since it doesn't follow familiar biochemistry. Even if it has a very obvious property, like the rubber-eating microbes from the Andromeda Strain, people will just test it for Earth microbes, get a negative, and go off inventing mundane rationalizations for a long time. Unless someone manages to culture the organism in a way that makes it obvious it's alive (so no living crystals that take years to grow) it may be a very long time before anyone realizes it. If you look at which bacteria are less studied, a very strong trend is that it's the ones that are difficult to grow in culture. You could even end up with a Semmelweis-type situation where a few people who do suspect the alien microbes are alive are ridiculed and ostracized.

If you violate assumption 3, it is likewise very plausible. Normally microbes spread everywhere easily, due to their rapid growth and simple environmental requirements. Even otherwise inhospitable places can easily provide good micro-environments for them. If your alien microbes are only able to survive in very exotic places, like inside active volcanoes, or they are simply so unaggressive that they are always a tiny minority of the microbe population wherever you go, it could be a long time before someone notices them. The problem is that if you have a microbe that's so rare it's barely there, does it really matter? The most interesting thing that could come out of it is that the microbe has some unusual gene or something like that which triggers a scientific breakthrough due to its theoretical implications. Maybe its DNA encodes a secret message. Who knows.

Violating 2 is the most realistic but also most boring. I think that if there was a way that microbes could escape into space and spread to other celestial bodies, then surely some of the untold multitudes of Earth microbes would have spread to nearby planets and asteroids. So the most likely source for alien microbes would actually be these "distant cousins". Moreover, if the alien microbes do have nucleic acids, they could be incorporated into Earth life through horizontal transfer, so the alien life would no longer seem unique due to that.

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