Could there be a living creature that is so old that part of it has fossilized? Here are some criteria I have for the thing to be described as a fossil:

  1. It has to be over 10,000 years old.
  2. A portion of it must undergo complete mineralization

I'm thinking of two kinds of creatures. The first is mollusk-like. It has a shell and lives in under-sea sand. This creature can live for prolonged periods of time, allowing it to mineralize. The second one I'm thinking of is plant-like. Again, it will live for a long time, eventually allowing its roots to mineralize.
What kind of environment could these creatures live in that will allow them to (partially) fossilize? What would their morphology have to be like?

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  • $\begingroup$ You seem to be asking about two creatures that may be quite different. Could you narrow to one and give us more detail to work with - tell us the problem you're facing that needs our help solving. (You can then ask about the other creature in its own thread, linking to this if you wish). $\endgroup$ Commented Apr 26 at 19:34
  • $\begingroup$ @Nitrogen-8 likely no as fossilization requires a living creature to not be alive anymore. If you want it to live the thing to be fossilized it must have been in hibernation for multiple 10 thousands of years. $\endgroup$ Commented Apr 26 at 20:19
  • $\begingroup$ This is part of ots body could be covered in rock which takes a very long time. $\endgroup$ Commented Apr 26 at 20:20

3 Answers 3


Fossilization as an external process is not likely to happen. Such an external process is where water carrying minerals pass through the organism replacing internal structures. This only happens when organisms die. If you want part of the organism to die and be fossilized while other parts of the organism continue to live, that would allow for some fossilization.

However, an organism can pull in minerals, concentrate them, and build cavities where those minerals can form crystals. This could be done so that the crystal forms provide certain structure to the organism much like how corals build reefs. It could use the crystals to build a platform for further growth, build for protection, or use them as a framework to catch food. When the crystals are internal, they will be wrapped in living tissue.


By far the simplest way to have that, is to design a creature that lives in extremely salty sea, essentially marinates in brine.

Imagine there was an inland sea that had some kind of extremely long lived crustacean. Over the millennia, the climate shifted, and the inland sea was cut of from most of it's freshwater sources, ans well as the ret of the ocean, and started drying. As it dried, the salt concentrated, until its water became thick, shallow brine that only a few creatures could survive in.

The Salt Crustacean is such a creature. Half-aquatic, it wades in shallow brine swallowing algae and insects from the surface. It metabolizes the salt away and allows it to dry into hard shell of salt on the outside of its body. Unlike normal crustaceans, the Salt Crustacean does not need to molt out of its shell, the salt continuously cracks and the gaps are filled with new crystals. Since the Crustacean is already extremely long lived/semi immortal, encased in crystal armor than no predator can gnaw through, and atop of that it is half-pickled in brine that kills most pathogens, it can live for tens of thousands of years, until it grows to the size of a small car, when the square-cube law crushes it under the heap of crystals on its back.

it could be that the creature's entire exoskeleton is near 100% salt, plus a little bit of chitin fiber to keep it together. It could also have lumps of salt in its stomachs to be used as grinding stones / abrasive salt gravel to grind food to pulp.


While the solution of David R is pretty good i got my own thoughts to add. Firstly i think there 2 Problems with what you want archive.

  • Firstly fossilization requires as David R you to be dead. Because minerals replacing your body is typically not an pleasant thing.

  • Secondly fossilization takes a very long time so your creatures has to be tens of thousands of years old as this is how long fossilization takes. An than is also there the problem with your creature naturally losing everything that could build up on it's skin.

But there are 3 Possibles Ways we can still make this work. Though please consider that they might not fit every of your requirements.

  1. Hibernation: Likely what fits your requirements the most. Essentially the creatures sleeps for 10.000+ years. Over the time Minerals form on its body and then it wakes up being partially rock.

  2. Fossilized Amor: Just imagine what happens to corals or ships over a long time. Essentially hard minerals build up on its body creating over time a partially fossilized layer. Though this only works with a creatures which skin does not shed or regenerate a lot.

  3. Mineral Consumption Similar to fossilization but much faster. Basically your creatures consumes minerals which it uses in it's body. It can quickly use them to have skin made out of minerals for example. And if you want the creature to be ancient just say that consuming the minerals slowly fossilizes part of its body over a long time. Think of it like how certain toxins can build up in a human body overtime but much slower.


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