Dose anyone know what this is???

[Kjtanks]

I was clean my tank today and move one of my corks and grown on the back of it I’m not sure what it is I have the coral in my tank for 6 months now and just moved it and saw this growing on the back I think it some kinda of flitter sponge if anyone can help Let me know what it is and if I should remove it or not?

 

[sfairtx]

Looks like a sponge to me. Helps filter your water. Aesthetically, its your call.

 

[KJ]

^^^ Agree.