The giant hermit crab[1] (Petrochirus diogenes) is a species of marine hermit crab.

This species lives in the Caribbean Sea, and often inhabits conch shells.

[2] This species of hermit crab is large enough that it can inhabit a fully grown shell of the queen conch.

It will attack and eat a conch, thus obtaining a meal and a shell.

[3] It was originally described by Carl Linnaeus as Cancer diogenes;[4] the specific epithet honours Diogenes of Sinope.