Can Someone ID This For Me?

[justinl]

yup, a sycon sponge. harmless and will probably reproduce in your tank no matter what you do.

[MMAX]

I've got quite a few all over the place. Had a large group at one time on one rock and they got covered with algae and disappeared. Then they started showing up in different places.

[Myka]

Scypha sponges. They're filter feeders, and help to polish your water. You usually find them in dark places like under rocks, in the shade, or in the sump/overflow.