What is this in my GSP

[marcmen]

Hi all, can anyone help me identify this white mass in my GSP? I noticed two of the masses have holes in them.

 

[Fredda]

I dunno what it is but think i have the same under one of my Blastos. Thinking is some fungus? Also have similar under a montipora, but that is yellow (on pic)

 

[marcmen]

Gotta love this hobby - I don't think I did as much research as I did when I was in school.

 

[shakacuz]

sponge. harmless filter feeder. not sure of the exact name of that kind, though

 

[marcmen]

sponge. harmless filter feeder. not sure of the exact name of that kind, though

All I needed to know - thank you