The picture is not good enough or at the correct angle to make a definite id, however, and this is just a wild guess and may not be correct. could be-
DISCOSOMA SANCTITHOMAE (=RHODACTIS SANCTITHOMAE) Warty Corallimorph.
-lighting - tolerates a wide variety of lighting conditions from bright to moderate.
-Range; Caribbean
-Food - Zooxanthellate, but does best if periodically fed small zooplankton, such as enriched brind shrimp.
- Good aquarium animal. Often reporduces well. Occasionally overgrows some other animals.
-Captive Care - this relatively common Caribbean corallimorpharian is easily kept and will clone itself repeatedly once settled into good conditions. It is almost intermediate in its morphology between other Discosoma and Rhodactis and may need a genus of its own. It is a robust animal with a rather stout column. Discs are sub-circular or elliptical. Color is bluish to green to brown. There is a fringe of small marginal tentacles and a region of large, often infalted disc tentacles surrounding the mouth. It reporduces asexually to form spreading colonies in nature, and will do so in captivity given proper conditions.