I need help with Coral ID

[Fluxion]

I bought this coral a year and a half ago, was told the name of the coral but I didn't write it down. Now I can't remember what it is. Can anybody ID this for me? Also while you are looking can you tell me what the white stuff is on its back side. I lost power at home due to an ice storm and have since lost quite a bit of corals and a few fish. I have been doing massive amounts of cleaning and water changes but I am now battling algae and then this white thing appeared. Please ignore the algae, I have already plucked it from the skeleton.

http://reefcentral.com/gallery/data/500/1032841.jpg


http://reefcentral.com/gallery/data/500/1032842.jpg

[Riona]

The white thing looks like a sponge to me. Then again I'm never right when I guess at things, so don't take my word for it :)

[650-IS350]

Looks like a scoly inverting inside.

[Fluxion]

Ha! Scolymia! Thats what it was! My wife and I knew it had a "SK" type sound in it. She swore that it was skeleton something so we have been calling it Skelator. In all my books I found pictures of button corals but they didn't look quite right. I have never seen a side view that shows the skeleton, only the top view.

I thought the white thing was some kind of a sponge, Should I remove it or leave it?