The term "Rock Anemone" or more elaborately "Rock Flower Anemone" is used for the species Phymantus crucifer from the Caribbean. An obsolete synonym still sometimes encountered is Epicystis crucifer. Rock anemones have the pinnate tentacles typical of Phymantus. Their maximum size is about 15 cm, which makes them ideal for nano tanks. Their contrasting colorations also make them extremely popular. The base color is normally gray to white, but green, purple, orange, yellow or red colorations are also possible, and the body, tentacles or mouth disc can each be 1-2 colored. Thus, particularly interesting multicolored specimens occur. It has up to 200 tentacles.
It prefers sandy habitats with coral rubble, where it can retreat into crevices or rubble when threatened. In general it is very faithful to its habitat. It has moderate demands on water quality, and has zooxanthellae and can feed purely on light, therefore it does not usually sting strongly.