Hard to tell from that pic but most likely a branching montipora digitata or millipora judging from the growth pattern. Could also be a stag but the branches are pretty thin.
Nice. I was also thinking staghorn. Unfortunately I dont have closer pics because its just a pic from google lol. I google pics of digitata as well Greech, but those seemed so much more thicker and packed together than this thing. Anyways, was just asking cause a large one would make a great centerpiece coral in my corner tank someday. I bet they're ridiculously hard though.