"Sunburn" coral??

[Jholli90]

Does anyone know what's happening to my birdnest? All of its polyps are extended out, and what isn't turning black looks pretty good. The black is getting bigger, and this has been going on about a month. All of my other coral (as well as fish and inverts) look really good, and are growing. It is my only SPS. The rest are soft, zoas, and 2 LPS. Parameters test fine. Temp stays at 77, and salinity is .25
Please help!

 

[Angel_Anthias lover]

Have you tried removing it?

 

[DangerDave]

+1 on trying to remove. It doesn't look like it's turning black, it looks like there is something black on it...

 

[scobeyra]

Yeah it almost looks like a sponge.

 

[Jholli90]

Have you tried removing it?

Well, I feel exceedingly stupid lol I hadn't even tried. It came off very easy. It had an algae texture. It was perfectly rounded. Any ideas what it is? Will it come back?

 

[Angel_Anthias lover]

Possibly cyano or a sponge glad it came off

 

[SeaDweller]

Yeah it almost looks like a sponge.

Yeah looks like a black sponge.