cannot really tell from the photo, it appears to be some type of zooanthid, hard to even id at that level without a better pic (read as better focus). Is it soft? does it have any stony skeleton at all? where did it come from? Does it change any from night to day?
How long did it take to increase the number of polyps from 5? (Pagoda's take a while to grow that much, and the polyps are not quite right) Skeleton? Rubbery mat at edges? All soft? Feeding behavior? Number of tentacles per polyp?
Even with all this info, ID will be difficult unless someone has an identical id'd colony, even then, just down to Genus usually. Better resolution on the photo will still help, and possibly pix from several angles as well as the physical description.
Spanks, possibly one of the Caribbean spp of zoos? Polyp morphology just doesn't look right to me for that...