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In some science fiction and fantasy settings (mostly fantasy) there are sometimes things like rock giants or rock golems. Basically, what I'm getting at is rocks forms with, sentience in some cases. So I was wondering if it is at all feasible for beings like this to evolve into human like creatures. They do not need to be made entirely of rock, I suppose, but how far from rock would they have to be? How would their bodies be able to function if it was possible?

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  • $\begingroup$ I think scales are probably as close as you would get. $\endgroup$ Oct 7 '15 at 5:58
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    $\begingroup$ . . . or shells/bones, which are essentially a type of rock. $\endgroup$ Oct 7 '15 at 6:14
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    $\begingroup$ like... erm... coral? $\endgroup$
    – user6760
    Oct 7 '15 at 6:46
  • $\begingroup$ Bear in mind these are usually animated using some external forces, not biology, so it doesn't really make sense to think of biological evolution. Think more along the lines of a robot made of rock instead of steel. $\endgroup$
    – MichaelS
    Oct 7 '15 at 6:56
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    $\begingroup$ relevant: How could something like a Gargoyle evolve? $\endgroup$
    – zeta
    Oct 7 '15 at 7:12
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Go for a silicon based life-form as most rocks have a high quantity of silicon in them. While not strictly a Rock-Being as we are accustomed to thinking about them in fantasy stories, a silicon based organism would share many characteristics with the Rock giants you want.

They will need to eat stone or stone like substances for food. As long as the evolutionary process is right, there's no reason they couldn't be as intelligent as humans.

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  • $\begingroup$ After they evolved into what you are describing could the walk around and live on a carbon supporting planet like earth? Could they survive outside of their planet? What would they need other than rocks to sustain themselves condition wise? $\endgroup$
    – Sunspear25
    Oct 7 '15 at 14:05
  • $\begingroup$ Your last question I can't answer because silicon biology falls into theoretical xenobiology. Conceivably they could survive outside their own planet and they may function in a carbon-based biome but may require some support mechanisms to make that happen. $\endgroup$
    – Green
    Oct 7 '15 at 14:12
  • $\begingroup$ I guess you cannot have silicon based life forms evolve at all. Our home planet has huge reserves of silicon, yet not a single multicellular complex organism that can digest rock or sand. The main problem here is that silicon based compounds are water insoluble and for digestion, water solubility is a must-have. No life form that we know of, can assimilate solid state particles directly into their metabolism. $\endgroup$ Oct 7 '15 at 14:41
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    $\begingroup$ Life doesn't have to use water as a solvent as there are other options. The trick with silicon-based life will be get it in an environment where carbon-based life can't exist or has a severe disadvantage compared to silicon-based life. Higher temperatures above 41C make carbon-based proteins break down. On a hotter planet, these kinds of conditions wouldn't be hard to come by. $\endgroup$
    – Green
    Oct 7 '15 at 14:44
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    $\begingroup$ Ok that makes sense. What would work as a solvent for them? I'm not sure if water would be a good idea (maybe it is I'm at a loss when it comes to biology of silicon life forms haha.) What would they most likely breathe as a silicon life form anyways or would they most likely deal with similar elements? Sorry for all the questions I'm just getting prompt responses from you. $\endgroup$
    – Sunspear25
    Oct 7 '15 at 15:06
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If you have a body made completely of rock, the best you can get is a statue. As far as I know, they are dead pieces of rock.

If you have a body with its skin made of rock, you are asking for the same thing. Rocks have zero elasticity as far as I know. So if/when your character moves a muscle, its body will crack at some point and it will bleed to death.

If you have a body made of skin like normal creatures but bones made of rock, this is not possible biologically. Rock is all silicon. Earthly organisms (all of those we know about) do not digest silicon or have systems for converting silicon compounds into rock. The closest there is, are calcium and phosphorous metabolisms, converting them into bone and shells (of sea creatures). Rock tends to be extremely weak when as thin as a bone. Also it is very much heavy and frankly it will hurt your hip muscles like hell when you sit down. Ouch!

So no, practically speaking, you cannot have any creature made of considerable quantities of rock inside its body or outside.

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    $\begingroup$ Barnacles and corals have squishy insides and a rock-like shell, as you yourself mention. So it is possible to have a creature with rock as its outer shell. But of course the shell/carapace is almost completely rigid, although according to this link: whoi.edu/science/B/people/kamaral/Barnacles.html , barnacle shells have openable "doors" with biological hinges. $\endgroup$ Oct 7 '15 at 7:42
  • $\begingroup$ In general, you are right. But specifically related to this question, your examples are out-of-place. In some scifi and fantasy settings (mostly fantasy) there are sometimes things like rock giants or rock golems. OP wants more mobile, intelligent and active life forms. Otherwise, he could even have gone for a en.wikipedia.org/wiki/Glyptodon which I reckon was the smartest of all shelled organisms. $\endgroup$ Oct 7 '15 at 8:08
  • $\begingroup$ Rock on the outside could work if it is segmented like armour. You would probably need a more normal skin for the "water proof layer" with the rock plates on top as armour $\endgroup$ Nov 23 '15 at 21:35
  • $\begingroup$ That is one side of the matter, as in, if a creature could survive with a rock armor. It is another thing to build rock (silicon) based armor from within the body. We are talking about a sand-eating creature here. Very very complex and unlikely, I would say. $\endgroup$ Nov 24 '15 at 5:14
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perhaps something like an assassin bug or decorator crab: instead of being literally made of rock, it sticks rocks to its outer hide as an easy means of self-defense. this would be pretty easy to evolve, as you basically just need sticky skin. this would let you have golems of multiple different shapes, sizes, and appearances. another fun idea: as the organism grows older, it could accumulate more and more layers of rock, eventually becoming so heavy than it transforms into a sessile adult form, more like a barnacle, and possibly changing into a female as well. at this point, its main source of nutrients would be any animals that wander close to whatever "mouth" it has, and it could reproduce by attracting one or more male mates and than raising the young inside itself. the crab comparison actually makes me thing of a rl example of what im thinking of: there is a species of crustacean that begins life as a standard, shrimp-like larva but on reaching adulthood enters the body of a fish and morphs into a network of parasitic fibers. the rock monster could work similarly: the young are hard-shelled insectoid creatures with stone shells, the second stage of life sees them start growing connective fibers and adding more and more rocks to their body, and finally turning into a large pile of rock-covered flesh with the original body in the center.

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Maybe you could want a silicon-based being.It wouldn't be very Earth-like (silicon cannot do all the things carbon does)and it would be very different, but, if we suppose intelligence evolves when it's needed to resolve adaptation problems, I think it could be sentience. Silicon can work where a planet is too hot to allow carbon to work (look at this). I hope it helps.

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No. A self-repairing self-building object will need an internal distribution network and units that are chock full of machinery for building and maintaining the unit, with structural support being a trade-off with all the stuff needed to make it work. Most of the stuff will be nanomachines intended to fill a role, not just be a rock.

In short, cells are full of stuff needed to make it live.

Bones are crawling with cells to dissolve and lay down mineral, and is a composite with protein as well as mineral, and shot through with blood. Shells and tests can be secreeted with various mechanisms, but require living tissue to generate it.

An armored creature or big shell is not what you mean, right? You are asking of rock = living tissue. It's not.

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  • $\begingroup$ The thing is it wouldn't be self repairing actually. One of the traits of the creature is that if it's injured it would be permanent. The reproductive cycle would be the hard part I suppose because then it wouldn't really be able to grow. I don't know I was just tossing the idea around. Also no, a shell isn't quite what I was looking for. $\endgroup$
    – Sunspear25
    Oct 7 '15 at 14:10
  • $\begingroup$ Then in what sense is it alive? Is it made of large-scale machine parts like a pnumatic bulldozer? Tyen how did it "grow"? $\endgroup$
    – JDługosz
    Oct 8 '15 at 1:19
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Since you're just "tossing the idea around", what about a being with a special affinity with rock? It's born as a biological being, possibly slug-like but long and maybe with tentacles, and capable of secreting rock-disolving acid (or has some other rock-shaping tools).

As it "grows" it's actually collecting the surrounding rocks and fusing them with itself shaping it to "build" its body, until it has collected enough rocks to form the armour or bones or whatever else you need to consider it a rock-person, while original organic bits form the muscles. At this point it's considered to be at full maturity.

The creatures could only be reared in rocky areas, of course.

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You could take some inspiration from Diatoms, they're coral-like free-floating algae that use Silica instead of Calcite to build an exoskeletal structure. Basically you'd have an inert "rocky" silicate layer wrapped around a life-form that is carbon-based and can be pretty much human in terms of biochemistry and anatomical structure. With the right structural considerations, under limb freedom and skeletal anchoring, you could easily have ten or twenty centimetres or even more of rocky material over your otherwise human analogous creature.

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You could have a creature that goes into a rock like state at various times in it's life e.g. as a form of hibernation (there are insects and fish that can survive being frozen) or as a very patient pounce attack. The creature itself is fairly humanoid normally but has this transformative process. If the process is very fast and controllable, in its now evolved intelligent form, it could lead it to something similar to the behaviour of the Weeping Angels from Dr Who.

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Let's make this one out of carbon. To keep things interesting, let's make that pure carbon, with no other elements, in a roughly room temperature environment. Let's put it on the Moon to avoid burdening it with too many extraneous gases.

Our ooh la la will come from this news story in which it becomes possible to herd phonons (sound vibrations) at an interface of silicon and boron nitride. These are both conceptually similar to diamond, and I'll assume without proof that the technology can be extended by a lucky evolutionary process. The article, which promises to move heat in arbitary directions within a larger structure, is some proprietary horror so let's look at an ArXiV preprint that seemed to predict it. They start off saying "Nonlinear effects open up a wealth of possibilities in quantum optics, harmonic generation, all-optical light modulation and switching, and nonlinear microscopy and sensing." Now that's almost a textbook list of features of life (if you squint at it hard) so let's describe our organism. We should consider the organism probably uses all the allotropes of carbon and would construct other structures at an atomic level only approximately describable according to any of them.

Power source is solar: energy is absorbed by deep black layers of graphene. These convert the light to phonon-polaritons in the short term. Reflecting early evolution, these photosynthetic organs serve directly as muscles, using the captured phonon-polaritons to slide or rotate graphene elements such as nanotubes, which are crafted in appropriate geometry to respond to this energy source. As with any thermodynamic system, the motion would be entirely reversible and random if the entropy were not dissipated: heat from the phonon-polaritons is radiated to space at some point on the outer surface. Note that these areas can be controlled and shifted at will using now-current technology.

Power storage relies on graphene-lubricated diamond latches. A "muscle" contracts, momentarily stressing the bulk diamond of the organism, and then it is latched into that position to store the energy. This mechanism also permits engineering for leverage well in excess of what the muscles can deliver.

Feeding means intake of more carbon, which is done by smelting carbonaceous chondrite using (ancestrally) sunlight focused through the diamond portions of the organism, or by focusing phonon-polaritons very precisely at a point.

Reproduction works a bit like feeding: phonon-polaritons from throughout the diamond flesh of the organism are focused to a narrow point, but tuned specifically to catalyze diamond-to-graphite transition. The result is that a new graphene photocell/muscle structure is constructed bisecting the organism.

The genetic code would be distributed throughout the organism at sites where carbon allotrope structures vary in a way that stores information. It might be seen as a prolific set of adaptions from the muscle structures that move in response to phonon-polariton energy.

I'll admit ... my reality check needs a reality check. :)

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