[Woodstock]

Without a picture it is impossible to identify them but it sounds like a type of planaria worm. Do a google search for "planaria marine worm", click on images, and see if you recognize any photos. Are they elongated and thin or flat and oval? The long thin type is a type of sandbed worm. A thorough cleaning of your tank and reduced feeding should get these under control. On the other hand, if they are the flat oval worms, they will be difficult to irradicate with mixed opinions on treating them(we can discuss those options if necessary). Either way, keeping the tank clean, vaccuming the substrate, iodine-dipping all new corals, and being careful not to overfeed will go a long ways to prevent infestation.