What am I

[theatrus]

Branching, massive growth, somewhat like a digitata. Excuse the red turf on it, it went through a rough spot and lost to a green stripe mushroom:

Loves light, fast growing.

Not a montipora, porites, or acropora polyp:

 

[Mael]

Pavona? dont think the structure qualifies as a psammacora.

 

[theatrus]

I think psammacora is spot on actually. It does first encrust and then branch.

http://www.melevsreef.com/pics/0903/0923_pics.html
http://www.orafarm.com/products/hardcoral/other/psammocora/

The coloration is a lot greener than pictured on my images.

 

[a.browning]

Branching Psammacora