Lampsilis siliquoidea with attached zebra mussels (Dreissena polymorpha), Lake St. Clair, Michigan. Posterior end view of the mussel shown previously. The zebra mussels have gotten inside the valves and prevent them from closing completely. Zebra mussels get their name from the zebra-like markings on their shells.
John B. Burch (photographer; copyright holder), Mollusk Division, Museum of Zoology, University of Michigan-Ann Arbor