This anemone (Calliactis tricolor) is often found on the shells of hermit or other crabs. Anemones are sedentary, meaning they must anchor themselves to a shell or rock. They have short tentacles with stinging cells for trapping prey. Crabs sometimes relocate anemones to their shells for protection or camouflage. This is beneficial to the anemone because it gets to eat the crab's scraps.