Perhaps Pavona frondifera
http://www2.aims.gov.au/coralsearch/html/401-500/Species%20pages/434.htm
The close up picture of one in Corals of the World Vol. 2 page 183 looks a lot like yours.
If I am right:
Sprung says:
Lighting needs: 3-9
Water Flow: 3-9
Aggressiveness: 7
Hardiness: 9
Placement: Chart shows that the species can thrive high, medium or low in the tank.
Best of luck,
Roy