nothing to worry about. They are called foraminiferans. They are a type of protista. Filter feeders. They wont do any harm. I have them all over my tanks.
but to make sure, go to the hitchickers thread on the top of the new-hobbiest section. It is somewhere in there. I had to look them up too a while ago cause i didnt know the name. I think they are under misalanious (god i cant spell) or something.