(Pod?) ID. Things growing in filter.

[hrdneglcry]

I would like to know the names of these things growing in my filter. I have some chicken liver sponge in one, or both Aquaclear 500's. But I'd like to know what the things are called that stick out like a stag's horn, or the little disc-like creatues that have starfish like legs. Here is a PIC I took during cleaning.

 

[greenbean36191]

The little things that stick out are vermetid snails. They're harmless filter feeders. In the main tank I find them annoying and kill them, but in the filter I would leave them. The other things look like they may be foraminiferans, which are also harmless filter feeders.