Is this an acanth or a favia?

[elliptical]

Bought it as a favia, so far opinions seem to be 50/50 over whether it might be an acanthastrea echinata or not? Any ideas? Thanks.

 

[SnowManSnow]

looks to me like a favia with tissue recession

B

 

[Anonymous]

It's definitely not a Favia sp. Favia have separated corallite walls, like this:

I think you're thinking of Favites, which has shared corallite walls. That looks more like an Acanthastrea to me though.