I think it’s the photosynthetic one. I think I only have one left in there which I can easily remove. I do also have the chicken liver sponge thoughChicken liver sponge? That's one I have in a lot of my tanks though they usually stay in the cryptic areas and I've always considered them beneficial. There is a black photosynthetic sponge that is invasive and will encrust over corals I'd avoid