Help identify place coral

[tc2007]

So I got a plate coral (Montipora?) it's dark purple with yellow polyps. I tried to take a good pic but it's hard given its size. The thing is it's not doing well.

So I would like to identify it in order to know about it's care level, placement etc.

 

[pstank1]

That looks sort of like a chalice, but it's tough to tell with that picture. They don't like nearly as much light as SPS do.