Not all life is good life

It is really hard to take photos of the tiny life form in my tank. So i tried to capture it on video. I wanted to know what it was, and how to protect it. I took the video to Tony, and asked him what it was. He didn't have good news for me. he said it is a aptaisia, and that it is a pest. He said it's okay to have it in the tank for now because it helps filter the water, but it can't stay. Apparently it will kill my corral, and spread until it takes over the tank.

So I have to kill it soon. I've read a couple sites that talk about using different way to kill it. I'll wait for Tony to recommend something. :(