Latley my tank has had all sorts of these things popping up. They're small, so far no large than dime sized, and look like small green/yellow sponges. Each of them has a small translucent tube of the same color sticking up in the center. Any ideas what they are? I'm not really worried about them at this point, since they don't seem to harm anything, but there's a fair amount so I'd like to know what they are.
Unfortunately I don't have a picture to offer.
Unfortunately I don't have a picture to offer.