Tiny little miniatures about the size of a matchstick with a soft tube?
Unless they're bothering something or affecting the health of a coral, I wouldn't be too concerned about them. They are for the most part harmless although quite prolific and will wax/wane based on the nutrient in the tank.
If they are truely a plague, a single peppermint shrimp would definately control them if not eliminate them for the most part. Once/if the pepp is ever removed, they will most likely return though.