Blue swimming worm?

Last night while examining my tank after lights out, I discovered a couple bluish purple worm like critters. They were not crawling on anything, they were being blown around by my pumps but every so often I'd se them wiggle and "swim" in the water. They are pretty small, maybe 1/4" long. I was able to catch them by sucking them into a dropper. I currently have them in quarantine until I determine if they are harmful or not. I'll see if I can get a picture later but they may be to small for my phone to get a decent shot.



Anybody have an idea what they might be?