That, my friend, is a flatworm. They aren't usually dangerous, but they can bloom to plague-like proportions. You should try to rid them now when you don't have much of them. Salifert has a product called Exit that works well, or you can try biological controls (which are hit and miss).
The White Flatworms rarely get out of control, if ever. They'll be nocturnal mostly and will eat quite a few pods. They use the front part to make a hood to capture tiny bugs that crawl on the glass.
Calm down gentlemen, as Guy said - those are not "those" flatworms. Those are cool. Are a good sign. It's a young tank, right? Don't worry about it, it's a good thing.