Ack what is on my mushroom coral?

[tobysmurf]

I managed so suck one up with my modified turkey baster, it was a worm about 4" long with the yellow bits on each end. They move like lightning so I was only able to slurp up one of the two that I could see on the mushy. I've had bristle worms in my other tank - mine were always grey-brown, never yellow. I think I am gonna declare war on these things just to be safe unless someone tells me that they are a helpful animal to have.