Calliactis tricolor, the Hitchhiking anemone;
Volusia county, Florida (22 May 2014).
The hitchhiking anemone is, as the name suggests, a fairly mobile species of anemone. Fairly small in stature, this species prefers to attach itself to more-mobile creatures such as mollusks and crabs. It is then carried around from here to there, reaping the rewards of more good eats along the way. Conversely, the Hitchhiking anemone also provides a bit of protection to its steward; it is capable of stinging would-be threats with a series of cnidocytes.