Could be goniopora if 24 tentacles. Or avleopora if 12 tentacles. If you just introduced. Should open up in a day or so. If it does not. It is not happy.
When the lights are on and tentacles are out. Will be able to determine which it is. Care is about the same. Avleopora generally like water a bit cooler. And will parish in less than a year if too warm. I find gonipora more hardy.
It looks like it is a gonipora. But is not realy extended or open. If your water perimeters are in check. You may want to try moving it in your tank. Try different lighting intensity.