Chef: This mussel recipe' s first step is to sprinkle the live mussels with cornmeal  The cornmeal is used to clean them out: they take the cornmeal in and eject the sand that they contain
But I can skip this step, because the mussels available at seafood markets are farm raised and ttherefore do not contain sand
The chef's mussel recipe was written before farm-raised mussels became available.