Difficult to tell from the photo, but possibly Hydnophora. If so, keep it FAR away from other corals as it will EAT them. Can you get a photo with the polyps retracted? Hydnophora has a very distinctive coralite shape that's easy to identify when the polyps are retracted.
how longs it been in ur tank>? I think its hydrophora too. Mine is more bushy though and yours will prob puff up and polyp more when its acclimated. +1 these corals are mean!