What is "porcelain crab"

Porcelain \Por"ce*lain\ (277), n. [F. porcelaine, It. porcellana, orig., the porcelain shell, or Venus shell (Cypr[ae]a porcellana), from a dim. fr. L. porcus pig, probably from the resemblance of the shell in shape to a pig's back. Porcelain was called after this shell, either on account of its smoothness and whiteness, or because it was believed to be made from it. See Pork.] A fine translucent or semitransculent kind of earthenware, made first in China and Japan, but now also in Europe and America; -- called also China, or China ware.

Porcelain, by being pure, is apt to break.
--Dryden.

Ivory porcelain, porcelain with a surface like ivory, produced by depolishing. See Depolishing.

Porcelain clay. See under Clay.

Porcelain crab (Zo["o]l.), any crab of the genus Porcellana and allied genera (family Porcellanid[ae]). They have a smooth, polished carapace.

Porcelain jasper. (Min.) See Porcelanite.

Porcelain printing, the transferring of an impression of an engraving to porcelain.

Porcelain shell (Zo["o]l.), a cowry.

Porcelain crabs are decapod crustaceans in the widespread family Porcellanidae, which superficially resemble true crabs. They have flattened bodies as an adaptation for living in rock crevices. They are delicate, readily losing limbs when attacked, and use their large claws for maintaining territories.