Please help ID this

[JenniB]

Hello everyone I noticed these things eating my elegance coral. I think it was on it's way out anyway but now I am seeing them living INSIDE my brain coral! I am freaking out over this. Sorry if the pic is big. 70 gal tank sg is 1.026 everything but nitrates is 0. Nitrate is super high 20 ppm (working on that)

 

[GerritM]

This is the "stomach" of the coral.

 

[JenniB]

Thank you

 

[wdg460]

Just notice same thing coming out of my mushroom...