What is this micro organism on my gouldian finch?

today i was cleaning my bird and then as i was checking his feathers, something white and tiny came squirming out of the bottom of his feathers. i took it off and then i put it on a paper towel. i notice it wasn't a worm but i was a ball and then it stretches out and goes back into a ball and does that over and over traveling slowly. i was wondering what it was and how to get rid of them if they are dangerous.