White fuzz on base of duncan anyone know what it could be

[iconics]

 

[MrReefkprZ]

I wish we had a clearer picture, because guess what this is is my favorite game. unfortunately due to clarity we can only spitball guesses and not even good guesses (and yes I understand it's generally very difficult to get a good photo of what you want) but guessing based on general shape and location I would say its a random filamentous sponge of unknown variety. and that is just a shot in the dark guess. if you can get clearer photos maybe I can do better.

 

[2quills]

I agree it's sponge. Not usually harmful unless it begins to smother the coral. Exposing the sponge to air would kill it if the plug isn't permanently attached to the rock.