I agree with the original answer of Galaxea fascicularis. That was my first instinct upon looking at it. My other guess was an oddly shaped frag of pagoda cup coral. Turbinaria peltata. The shape of the frag made me think galaxea but the tips of the polyp tentacles made me lean towards turbinaria.
But after really looking at it I can see that that is a super close up picture of it on the frag plug so I would have to guess Green cyphastrea simply based on the polyp size and shape.
Do the polyps look like the coral in this thread? Disregard the coloring and focus on the form of the coral itself.