To clean mussels, discard any broken-shell or open (dead) mussels. Scrub remaining mussels in cold water, removing any barnicles with a dull paring knife. Pull beard by giving it a tug (using a kitchen towel may help). If you have trouble removing it, use a pliers to grip and pull gently. Place mussels in large container. Cover with cool water. Agitate water with hand, then drain and discard water. Repeat several times until water runs clear; drain.