Rescue tank has some sponges and... things? growing in it that I'm trying to determine if they need to be removed or at least controlled. They're mostly sponges, though the stringy ones on the back of the tank seem to be something else. Any ideas on them? I know to keep sponges out of my equipment, but I don't mind too much if they're growing in the dark corners of the rock, as long as they're nothing dangerous to the corals or livestock.