Background: nacre/mother-of-pearl is a strong composite material produced by mollusks, with a greater compressive strength then human bone but a weaker shear strength.

If an entity were to have bones that were composed of both bone and nacre, how would it interact with the world differently? For instance:

  • said entity can jump from higher heights without damaging limbs, provided that they land in a way that channels the force of impact parallel to their leg bones, rather then perpendicular to it

  • said entity can punch harder without breaking or damaging their arm bones

For the purposes of this question, let's say that this entity can regenerate bone tissue as effectively as "normal" life can, and that its connective tissues are proportionately durable (say, made of resilin).

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    $\begingroup$ Thinner limbs with tougher bones defeats the purpose of having tougher bones. That wouldn’t make the entity any more resistant than usual. $\endgroup$ Commented Aug 12, 2021 at 9:53

1 Answer 1


Nacre and bone play very different roles

Bones are actually used as stockpiles of calcium for the body to use in metabolic processes, like for example muscle contractions. This is why bones are constantly being formed and dissolved. Nacre on the other hand serves to protect soft bodied animals from external harm, or sometimes rough grains of sand, which are then covered by nacre to form pearls. These different roles are why we don’t see bone and nacre skeletons in nature.

A likely way to have both is for the nacre to form inside the bone near the marrow, though unlike bone which is constantly being broken apart the nacre may accumulate and grow constantly. This shouldn’t be a problem if the entity sheds the nacre like cuttlefish shed their cuttlebone. This would occur very slowly over the course of decades, so the bone surrounding the nacre would have time to let it out.


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