Right: Photograph of the plumose anemone Metridium
senile (L.) by Ron Crosby.
Common on wreck sites, metridium will colonise any hard substrate where
there is a strong current to bring food to it. Metridium is distinguished
by having a mass of fine feeding tentacles (usually rather finer and more
numerous than in the example here) and a prominent ribbed mouth. The tentacles
can be withdrawn very quickly if disturbed.