This tiny Starfish shrimp lives on a blue Starfish. If you find an orange or red or yellow (large) Starfish you may find similar shrimp colored to match their host. They are tiny, and jump always to the underside in a flash. You will only ever see one if you lift the starfish and look at it's underside, at which point it will jump to the new underside. Handling is forbidden in some places, and bad form everywhere, but these guys will always be on the underside of a Starfish.
From Ikelite Photo school