What is "dreissenidae"

The Dreissenidae are a family of small freshwater mussels, aquatic bivalve mollusks. They attach themselves to stones or to any other hard surface using a byssus. The shells of these bivalves are shaped somewhat like those of true mussels, and they also attach themselves to a hard substrate using a byssus, however this group is not at all closely related to true mussels, being more closely related to the venus clams ( Veneridae).