Whatever it is, it is very recessed. Fungia would be my first guess, but it could be something related like a scolymia. Have to see a better pic, one with it inflated so we can see the tentacles.
It is really mad in the pic lol. My pal had just fragged it for me. Its soo cool when its all jelly like inflated. Are they a rare coral? I dont know a thing about the scoley?
Fragged it? Doesn't look like a frag. I thought things like fungias the only way to frag them is to cut them in half/quarters making sure to get a piece of the mouth on each frag. The normal way they spread is they just pop out babies, mini versions of themselves. Actually seen that more often than I have seen people fragging them since they are one of the more difficult corals to frag successfully.
I hope all goes well then. He just cut the side off. It was in a rectangular shape. I think I see mouths on it. Lil eyes like the center of a zoo. Its kinda got bubbly'er. My buddy said it would take a couple days.
He had it on the gravel in a 20gL with 150w MH phoenix 14k. Im running 40w PC. This sat im getting a like new (4month old phoenix 14k bulb) Coralife 150w pendant.
I will have to agree then with Amphiprion. It is a Halomitra, which is similar to a fungia, but not the same. Hopefully Amphiprion can chime in and say if the manner it was fragged was ok.
I can say I have never seen one of those before, and even google comes up with very limited information on them, so I would guess it is semi-rare at least.
Edit: From this picture it does appear to have multiple mouths..