White things "growing" on glass?

Well about a month ago I noticed a bunch of white specs on the inside glass in the tank. At first they were so small I just thought maybe the snails were laying eggs or something on the glass. Well through cleaning the front and sides were cleared of them, but the ones on the back were pretty much left alone to grow. They are small and white, shaped roughtly like a piece of rice. They appear to be attached to the glass with a bunch of small arms/roots/tenticles, etc... not sure where to even start to find out what they are. Any ideas what the are or where I can research them?

Rick

Well I have gotten a better look and the length of the "body" is anywhere from a few mm to a cm or so, the tenticles are structured alot like roots of plants, looking like branching arms. They look like the tips of small Q-Tips with roots growing from them. I am lost :-/

Rick

Thanks for the responses. They look very similar to the q-tip sponges, I will look for some more pictures to be sure, but thats my guess so far, thanks alot guys.

Rick