Brown root like organism

[Jeeper]

I'm gonna call them ant worms because they move together like a army of ants. I think they are algae eaters, as I cleaned all but the bottom 3 inches of glass this weekend and that's where they stopped. The few I have seen away from the tentacles have been 1/4 to 3/8 long and they move back into the group. I have not seen them leave one behind on the glass but they are very very thin and hard to make out individually.