I recently came across a game called dead space and a certain main antagonist species inside of the game. In this game you play as the main character who is trying to protect humanity from sentient race of beings called the the brethren moons.

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These are creatures that can reach a massive size of 2000 miles. They live in the void of space feeding off of intelligent species that become over populated throughout the galaxy.

Ignoring the evolution aspect of the creatures and where they would of originated from. What I want to know is if such a creature that size could even survive and reproduce, and what would happen to the core of the creature if it was that size.

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    $\begingroup$ A touch larger than you were thinking, but: Obligatory XKCD $\endgroup$
    – Joe Bloggs
    Commented Nov 20, 2018 at 17:37
  • $\begingroup$ By the lore, didn't the brethren moons only use intelligent lifeforms for reproduction? As far as I remember the lore they are powered solely on the black markers (infinite energy sources responsible for the dead tissue they're made of being animated to begin with) in the center of their bodies and only rally use the intelligent lifeforms to create more brethren moons (aka reproduce). Come to think of it the new black markers they make are borderline meant to work as a brethren moon seed. $\endgroup$ Commented Oct 8, 2021 at 14:37

5 Answers 5


Almost certainly not.

But that's not much fun, so let's try and think of ways to make it even remotely plausible:

First, the creature could use an actual moon or large asteroid as a core; i.e. the biological portion is only a relatively thin (though still stupendously massive) layer on top. This would dramatically cut down on the energy required to reproduce, and give it a structural core that it didn't need to grow itself.

The host planetoid could be the source of most the raw materials for the actual creature. It could also serve as a giant heat sink/source to help stabilize its temperature. The creature could dump heat into its core when energy is plentiful (when near a star, or feeding,) and draw upon it when it's scarce (i.e. in deep space.)

How it moves is going to be a problem. Barring science fiction Warps and such, the only remotely plausible (still nuts, note) method I can think of is something like a planetary-scale ion drive, where it continuously accelerates and ejects a small amount of core mass at extremely high velocity. Very little thrust, but excellent efficiency. It would also take advantage of gravitational slingshots as much as it can (being intelligent would be very helpful here.)

All of this means that the sucker is going to be very slow. You can model it pretty well from the more realistic generational space ship ideas. Hundreds if not thousands of years between target systems, during which it will need to be in a basically-dead hibernation state ("In his house at R'lyeh dead Cthulhu waits dreaming...")

Then of course there's the issue of how & why it feeds on intelligent species... In any realistic scenario it would be much easier and filling to just feed on stellar radiation. You'd pretty much have to have a "psychic energy" angle in your world to make it plausible. Which given the Lovecraftian nature of the critter you may well have anyway.

  • $\begingroup$ great ideas, and I agreed with you on how intelligent species is a bad food source. when I posted the question, I was thinking that it would use solar radiation for a food source instead of what the game says it's food source is. $\endgroup$ Commented Nov 20, 2018 at 18:42
  • $\begingroup$ I am not sure ion drive is needed. If extremely slow is enough it can simply control the heat distribution of its surface. The heat will radiate away in the form of photons and the photons will have momentum. So if you can keep the heat distribution unbalanced you can apply momentum to yourself. Very slow obviously but you need to manage your heat anyway and it uses zero reaction mass. $\endgroup$ Commented Mar 19, 2019 at 8:22
  • $\begingroup$ You can also use the photons from the sun by changing your reflectivity. Those photons also waste zero reaction mass and they have higher momentum than thermal photons. $\endgroup$ Commented Mar 19, 2019 at 8:24
  • $\begingroup$ Using the moons mass for the ion drive might may things for efficient. Use the organic ion drive to throw bits of the moon in directions opposite of travel. Effectively it would eat the moon over time and have to find a new moon to use. $\endgroup$
    – Kezat
    Commented Sep 17, 2021 at 6:25

Not in real life, no.

  1. A 2000 mile diameter organism would be between the size of mercury and mars. This organism would crush itself under its own gravity and die.
  2. Keeping that much organic material alive and warm in interstellar space is very costly from a caloric intake perspective. Devouring an entire civilization would not provide enough calories to keep it warm and alive.
  3. Movement, moving something this size requires an enormous amount of energy, which it can only get from devouring an intelligent species, but it would have to use much more energy to get itself from solar system to solar system, and it may or may not find an overpopulated species in a system it visits.

There are surely other reasons why this would not be possible, but it mostly can't be reconciled due to the energy requirements of such an organism. This guy really needs some sort of ship with a handwavium power source in order to do what it wants.

  • $\begingroup$ If possible, can you think of any solutions to these problems and what it could do in order to survive? $\endgroup$ Commented Nov 20, 2018 at 17:58
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    $\begingroup$ There no way with physics as we know them. Only with heavy modifications. $\endgroup$ Commented Nov 20, 2018 at 18:02

Just to add.

  • Energy

Your creature is close in size to Earth's moon and lets take the same for mass.

Just on fast calc for energy needed to move (hope I did not mess up), with perfect antimatter-matter conversion: To move in or out would take around 350 million tonnes of humans(???) And you need to go in and out and have food for your body, savings, extra movements. I would say, it would need minimum of 1 billion tonnes from each planet it visits. For note, 1 kg is ~43 megatons, not so far from Tsar Bomba.

All humans on Earth would be around 500 million tonnes so not even worth a trip fuel. But you can eat some trees for salad and go find something more fleshy.

  • Pressure and heat

Pressure and heat inside such creature would be massive. The temperature in the core of Moon is probably about 1600–1700 K. There is no way any life, with no magic involved, that would live with that.

But there is solution! Creature is only some 50 km thick and center is close to hollow or has real moon inside, taken as home by creature.

Close to hollow structure would lower energy needs and make viable more real ways-to-get and manage energy.

  • $\begingroup$ i agree with you on the hollow part, that is a pretty good idea $\endgroup$ Commented Nov 20, 2018 at 19:33

Yes it is fairly possible. I'll add a little more information as you can't ignore or skip over the hows and whys when discussing anything.

As a cullular manipulator the breathern moons/Necromorphs would have capabilitys we see in nature, like deep sleep hibernation stasis, cellular regeneration and surviving without need for food.

There is bacteria that was discovered outside of earths atmosphere on a satelite. Bacteria that can survive in the void/vaccum of space, as well as viruses(more specifically pyrons and a little dabbling with crispr to create a super virus) that can potentially forgoe alot of what we know about biology.

Plus the way these moons are created and develop are fascinating. Development Points that shouldn't be ignored when discussing things beyond ourselves in the limited perception we have of our place in the universe.

People are missing many of the realistic aspects of what necromorphs and the markers are. The breathern moons are just a product of the assimilation process caused by their energy source.

The real cause of how they begin is there are two distinct sets of Markers. A black one and many red ones produced by intelligent life that just so happened to be unfortunate enough to come across the black markers, or lead to reproduce them. The black one acts as a radio beacon or a relay thats connected to the other breathern moons.

For awnsers to some of your questions about how they move and their energy source, as well as how they are created. See the background information and where the developers have pulled their inspirations. They tended to get too imaginitive with the reality of science though.

black markers are sent out by these giant masses of infected living flesh and dead flesh. Creates a signal that draws intelligent life to it or creates lesser intelligent life to evolve to a higher conciousness. We are after all discussing entitys that are practically gods compared to us humans.

Every breathern moon is another previously assimilated intelligent species thats been cultivated and usually evolutionarily forced to a higher consciousness through the frequencys abilities to alter brain function. Consider the game to be in itself a darker horrifying theory on the theory of life in the universe. Its much more of a self exploratory look at cosmic horror.

Its unknown as to how it creates these black markers but my best educated guess is probably from iron and some other things to create an aloy from the blood in our own biological systems. Giving it structural support that can reinforce into steel with the already present carbon and resources pulled in through its assimilation process. Adding on to the hollow layer theory which could also allow it to propel itself through space like a jelly fish or octopus.

But the black marker itself is both a limitless power source that creates its own energy through some highly advanced use of frequencys that also effect psycho/nuerological brain function.

The red markers are the source of a reanimating bacterial(realistically it'd be a super multicelled virus) disease through airborne contact or direct infection from the freshly reanimated bodies that aren't fully dead. As the brains consciousness may die but not at the cellular level giving the bacterial or more realistically a super multicellular virus that can hijack the hosts reproductive cellular mechanisms.

As well as emitting a frequency that can not be heard or measured let alone have any safe gaurds created for many reasons. I.e its ability to alter the mind. Im guessing this frequency could also use the solar winds or energy and sail upon those or know its direction. Or as mentioned in the above posts using gravitational pull and slingshoting.

As it is a more natural free hive mind in a way that doesn't need to control everything it has used as its weaponized drones.

This frequency is where its limitless power also comes from. As the shape of the marker apears to create the ideal structure to let the frequencys bounce and absorb through a complex generative absorbing crystal structured like an acoustic/rely that allows them to have a limitless source of energy. One we and any advanced enough life form would see as absolutely the greatest find for our own technological advancement. Which would somewhat explain where it could generate enough power to create the assimilation process once intelligent life produces more markers.

The frequency then allows for a change in intelligent organisms behaviour, starting as a drive to recreate the marker. But it hides its true intentions behind this drive like a religous ferver. Tricking intelligent life capable of reproducing the red markers into creating many so the chances of total assimilation are secured. Isaac clark the main protagonist as strong willed and capable as he was. Also suffered the effects upon being in a rather far proximity to one marker.

As size of the markers don't. Really matter. But the red marker is different to the original black marker. Red ones emit a psycho/nuerological frequency that instead of drawing those towards wanting to understand and recreate it. The red ones turn intelligent life insane or suicidal, or pursue its cause to make itself whole.

Turning intelligent life insane, violent or suicidal. Is a very real and scary fear that we have some counter measures against. But because of of the widespread chaos feom a behavioral collapse allowing for the bacteria to spread and infect dead cells until it gets to a critical mass.

Where it then pulls in all the dead and living matter with a gravitational pull that also pulls in other matter. Buildings and loose earth. Even a fragment of the red markers emits the signals frequency.

The horrifying part that exists in our reality. Is how these Markers emit frequencys that can change human behaviour. As well as the use of this frequency as an energy source.

Now lets say the bacteria that lives in the vaccum of space, works the same as the infectious necromorph bacteria. but this bacteria repurposes and reanimates cells like a super multi celled virus that can also infect living tissue in the freshly dead, or the willing or unwilling living hosts. Which can create stronger replicating living tissue which created the regenerating hunter in game. Repurposing tissue to have the capability to survive in space.

A reason that something that large could then exist in the vaccum of space would be its hijacking ability to overide natural safety switchs and the ability to repurpose bio organic material. It could create a membrane around itself that could fight cold and radiation or adapt to whatever needed, which could then also repurpose some of itself to become the tendrils to propell itself through space. Or act as a means to sense and help rely signals from different directions to the other breathern moons.

Theres alot of complexity put into the thought and background of the Breathern moons.

The game is rather scary close to reality and many wouldn't want to know the truth behind certain aspects of cosmic horror. The things beyond our fear and understanding of the universe much like if one could peek into the 4th dimension.

Low frequency that could potentially be manipulated to create limitless energy.


The impact frequency can have on humans. https://www.ncbi.nlm.nih.gov/m/pubmed/16201210/

The bacteria that can live in the void. https://www.google.com/amp/s/phys.org/news/2016-03-bacteria-space-earth.amp

How a super virus/bacteria that is multicelled could have the potential ability to hijack our cellular reproduction. And just a bit extra on how dead cells can be manipulated.



The frequency that could potentially be emitted that could effect human behaviour and the brain. https://www.physiology.org/doi/full/10.1152/jn.2000.83.6.3548

Mind you this is nothing more then speculation and theory on the existance of life that is greater then ourselves on the cosmic level. I am also having trouble finding the sources where i've drawn more darker information and my own conclusion so I will not be adding that extra stuff.

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    $\begingroup$ Hi, I think this answer is more of a description of how the brethren moons work in 'dead space' rather than being based much in physics and biology. While it is interesting I don't think it is very useful for someone trying to build their own world. $\endgroup$
    – user42528
    Commented Mar 17, 2019 at 7:01
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    $\begingroup$ Welcome to the site Herald of leviathen, please take the tour and read up in our help centre about how we work: How to Answer I agree with Ben, that whilst interesting, your answer doesn't provide an actual answer to the question. Get to know our culture here by taking a look at our help center . $\endgroup$ Commented Mar 17, 2019 at 7:54
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    $\begingroup$ Well first of all, one would have to understand how and why the breathern moons exist and how they function. The developers actually did research even if exaggerated in some aspects. The theory the game is based behind after all is where it gets its name. Giving a chilling thought of us being nothing more then a domesticated animal to something beyond our small world. I will be adding my sources and the physics that would allow such horrors to exist. Mind you It is not absolute, but it is alot more realistic then most scifi games out there in certain aspects. $\endgroup$ Commented Mar 19, 2019 at 0:10

The one thing in terms of movement i think everyone forgot is how large this creature is. If it manipulates its mass just right then it can probally physically change its mass in specific ways to effect its own gravity. By shifting its body the right way it could probally create literal gravity sinks and use the gravity to accelerate its body. If it does have a hollow middle then its gravity may not even be focused on the center of its body, so how it changes itself could allow for it to use gravitional waves for movement.

Also we are assuming it is just a bacteria, when it could also be fungi(take a look at what cool things mushrooms can do to change the air currents) , or nanomachine given the pillars.

But yeah, if anyone ever suggests to me a moon looks 'meaty', just contact Nasa and request every weapon available. Safest choice.

  • $\begingroup$ "By shifting its body the right way it could probally create literal gravity sinks and use the gravity to accelerate its body." That would be analogous to pulling yourself up by your shoestring. At best, they'd just be able to wobble back and forth a little. $\endgroup$
    – nick012000
    Commented Sep 19, 2021 at 1:07

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