Unknown growth underneath Frag Plug

[OuiWii]

I've had this plug in my tank for about 2 months now and picked it up today to inspect it. The coral mounted to the plug is a Plating Monti thats not doing so great.

This plug has been stuck into a hole in my rock this whole time, so this creature ah the bottom of the plug has been growing down there without much or any light. It appears translucent.


Any thoughts?

 

[nex64]

Looks like a sponge

 

[35ppt]

Redacted

 

[ZipAdeeZoa]

Pineapple sponge on the very bottom (good guy, harmless filter feeder) and surrounding it appears a different kind of sponge.