So far, we see an alien life form depicted based on earth type of animal kingdom, we see an insect like Zerg, a humanoid grey alien, etc.

However sometimes we see alien like Guardians of galaxy's Groot, Transformers robotic alien, and others.

The question:

Is that possible that an intelligent alien life form that can think complex logical thought, communicate with each other (and with us possibly), can move freely (not rooted on the ground), not in microscopic scale, and not evolve in animalia kingdom path (it can be based on earth's fungi, plants, algae, or anything even sands or magma just not animals in the taxonomycal branch) can logically exist? if yes, how would it evolve?

It can be walking plants, an intelligent crystal, a living planet to an interplanetary gas form of being that can move and think according to its own will.

Edited: It should developed naturally (no involvement of other alien/human to kickstart, or managed the evolutionary process)

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    $\begingroup$ Yes. It can logically exist. Perhaps it could be intelligently designed by humans or other aliens, although I'm sure that alternative paths of evolution are also possible. $\endgroup$
    – ohwilleke
    Dec 1, 2016 at 7:01
  • $\begingroup$ Oh I will edit it. No it couldn't be an unnatural process by other intelligent beings like us. $\endgroup$ Dec 1, 2016 at 7:15
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    $\begingroup$ The answer to 'can it exist' is yes. The answer to 'how would it evolve' is too broad of a question. There are too many possible answers. You should, perhaps, try to come up with an alien form and then ask for help developing a logical evolution of it. $\endgroup$
    – kingledion
    Dec 1, 2016 at 7:20
  • $\begingroup$ oh ok, should I delete this question then? since I don't have any favorable in one life form and just curious about it. $\endgroup$ Dec 1, 2016 at 7:41

4 Answers 4


What it must have is:

  • Memory
  • Processor
  • some use for those

For animals it is brains. I think that the best possibility could be fungi. If you would add some data processing power to fungi you could get slime fungus that can think. Instead of being an automaton the fungus could think where to expand. This would let it manage its growth and to optimise, not just rely on heuristics from its genes. It can remember the new routes of animals (or something else that moves) and spray the spores to them. It can also make decision to expand just for the exploration. The fungi could clearly benefit from the intelligence.

The next step would be a slug like movement. The intelligent fungus that sees a good spot would not like to rely only on spores and expansion.

After that, ocean and then the similar path to human or something like that. If it is OK to restrict the movement within water and not to communicate with humans, then there is no need to make it a land creature. The problem is that the cells need to specialize to muscles and such, if it is not only slime.


The first thing I thought of when I saw this question was the C'tan from Warhammer 40,000, clouds of extremely energetic thinking gas. In theory as long as there's a "gating" mechanism for data transfer and decision processes you can have intelligence on any scale, a semi-crystal that's able to undergo chemical transformation ripples can transfer impulses along a network similar to the human nervous system in operation, in theory you could have thought processes handled by a computer-esque chemically doped quartz crystal, although how that propagates itself is anyone's guess.

Although any of these mechanisms might be used as the basis for something that moves and possibly communicates I'd expect that the better starting point would be algae since many species can move under their own steam already, there are two routes you can go with this as a starting point, colonial or solitary multi-cellular. A solitary multi-cellular algae is basically going to be a "planimal" a mobile plant that acts much like an animal in that it moves to the resources it's needs to consume but plantlike in it's metabolic processes and requirements. A sentient colonial form wouldn't look or behave that differently to outward appearances but it would differ greatly in structure and instead of being intelligent in the normal sense it would have a highly evolved swarming instinct. Both of these can be asexual reproducers the colony splitting when it grows too large and multi-cellular beast undergoing binary fission or some kind of spore release in the name of spreading itself around.


Taxonomically, the kingdom Animalia is exclusive to earth life, just like any specific taxon: family, genus, kingdom, phylum, class or order. A taxon, such as the kingdom Animalia, technically refers to a group of organisms that have a common ancestor within it’s evolutionary path somewhere upstream. Alien life does not have the same ancestor as earth life, therefore, even if there is an Animalia analog on some other planet, it will not be in the same taxon as, nor it will be a member of the taxonomic kingdom Animalia, which denotes the descendents from an organism on earth which all Earth animals evolve from.

Simply say, Even if your aliens are animal like, it will not be a member of the kingdom Animalia, which denotes all Earth animals that descends from a common ancestor, but not any Non-earth animals, such as aliens.

  • $\begingroup$ This is on the verge of being a non answer - while technically true I think OP was looking for something a bit more biological, rather than the technicality of how we categorize organisms. $\endgroup$
    – bendl
    Jun 18, 2018 at 16:26
  • $\begingroup$ This thread's question started from a similar thinking much like this answer. As this is logically plausible. However the question is about what are other possibilities considering almost if not all alien life form depicted is always just lazy funky copy of what's life on earth. Therefore I asked about other possibilities, rather than just make them have 6 hands, eyes popped out, or just plain big lizard that reproduce by spores or other boring this you see walking around MIB movies. $\endgroup$ Jun 19, 2018 at 1:48

The problem is we do not have any similar experience to relate so we just cannot answer. We can only refer to an evolutionary path that we have observed/experienced. And truth to be told we may even underestimate what we see when we observe something. For years animals were devoured of emotions, however, most recent studies show that at least some mammals have pretty much the same biochemical mechanisms as humans. Moreover, recent scientific studies suggest that plants do feel, even though we may say those feelings aren't necessarily the same as ours.

We have observed these as life forms because they are at least in some way similar to us and we were capable of applying the same thinking logic as we apply to us (or at least have a link going through the path of comparison with species gradually linking us to plants). But can we really see a life form when we look at it? How can we even define what life is? We will always relate in some way to us? Can we call black holes a form of life? They consume (material), execrate (radiation), evolve. Do they procreate? What about things we haven't yet encountered?

Famous Polish sci-fi writer, Stanislaw Lem, has considered this in many of his novels and works. You may also find those considerations in other sci-fi works, e.g. Ender Games series by Orson Scott Card.

Shortly speaking - it may be possible but there is no way to prove it. Even if it is possible we do not have sufficient knowledge to surely define such an evolutionary process. IF we manage to artificially create some form having all traits of life or we meet some life form other than carbon-based, we will be able to answer for sure. Other than that the only answer we can provide is "we don't know". The way life on Earth was created is so improbable that I don't think we could imagine it ourselves. We had to analyse the process based on what we know and reach some conclusions.

On the other hand, since the way our life started is so improbable, it is quite improbable that no other way exists. We just are not capable of imagining it. So funnily enough, it is quite probable that completely other life forms (e.g. silica-based) exist or can exist somewhere in the universe.

One funny remark here. In mathematics, if something has very, very low but non-zero probability then it means it exists (otherwise the probability would be 0). I have seen proof of the existence of some functions with very specific properties by proving they have a very small but non-zero probability. With the scale of the universe, you can actually assume the same principle.

Finally - all examples you have included in the question can be some life forms (well, the biggest problem can be with planets as they hardly can control where they go and evolution itself is highly difficult to imagine). So just pick one (or more) and try to work on how to define the evolutionary process leading to them. Try also checking other questions, chances are someone already asked about evolution of such non-earthlike life forms.


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