noun
sponge crab
A species of crab (Lauridromia dehaani) that carries a sponge on its back for camouflage.
カイカムリは背中にカイメンをのせて身を隠す。
The sponge crab hides itself by carrying a sponge on its back.
The name literally means 'shell-wearer' (貝被り), referring to the crab's habit of carrying a sponge or shell-like object. The exact derivation is uncertain, but it is a straightforward descriptive compound.