It looks like a Leptastrea but it could also be some type of Gonipora. If you could see the polyps pulled in, so that you an see the skeleton, you would able able to id it better.
If you not familiar with Leptastrea the polyps look a lot larger in the photos then they actually are. Most picture are taken very close up.
Here is a picture of a Leptastrea from Atlantis web site so you can judge: