what ON EARTH is growing on my duncan

[egrape]

I've had this Duncan for about a month and a half now, and at first I was struggling with some tissue on the Duncan deteriorating. Nothing major, i never lost any heads, but just enough tissue loss to worry me a lot haha. now, it's almost fully recovered, still a few bare spots, but it is working on growing four new heads! anyways, today I was looking at it and seeing how much the tissue had regrown and I turned it around and there is this bizzare white spongey thing. I freak out and violently knock it off my Duncan, so now it's floating around somewhere in the tank, and then I find another. thinking a little more rationally, I take a few photos and leave it be. what is it? do I remove this one too? these dudes appear to be growing on the only two remaining bare spots. ive had to fight off creatures before while the duncan was healing, i had a snail that developed a taste for dying duncan flesh, but never something like this... IM SO CREEPED OUT.

 

[egrape]

here's another photo. the Duncan's a little unhappy with me right now after the brutal assassination of its hitchhiker, hence why it is closed up.

 

[Massimo]

It's probably just a sponge. Harmless to the coral, I had some growing beside a bunch of mushrooms, they did no harm

 

[randy07]

I can't see it real well but im pretty sure its a pineapple sponge there common in farely new tanks.

 

[egrape]

phew. yeah I think so too. so should I remove him or leave him?

 

[randy07]

Id leave it. Its not really hurting anything and it will die off eventually anyways. That's just one less time that your hand goes in the tank and that's always a plus.