Thanks guys! They do look like hydras. Since I don't have any fish in the tank I think that I'm gonna let them do their thing for now.
I read that fenbendazole will kill them off really easily so I'll just use that if they become a nuisance.
It's sorta cool having teeny freshwater anemones in...
http://i.imgur.com/5q9cSt9.jpg
On the left, midway down the driftwood.
They look like teeny white/transparent sacks and they are attached to the glass by a little thread. (The longer threads are just moving bubbles)
The picture has the largest cluster of them but they are otherwise pretty...