It is a flatworm. Hard from the photo to determine the type.
Based on your join date, my guess is that this is a transient population boom that will subside on its own. So you may want to wait before trying to treat or adding a fish.Thanks for the reply.
I don't see they are doing any harm to anything. But they are getting to be an eye sore. It seems that they migrate in the tank literally in circles covering the glass and rock. The only difference that I noticed is that I don't notice my reef bugs at night now.