Are these sponges?

[peewee5779]

Are these yellow clumps growing on the back of my rocks sponges? If so do they have a specific name/type?

 

[bubbgee]

Yes, looks like it is.

 

[KrisReef]

Yes, they have a specific name but I don’t know what that is.

My main server got burned in the 70’s by frequent exposure to Disco and stuff