Atlantic ribbed mussels, Geukensia demissa (Dillwyn), protruding from the salt marsh clay sediment at the base of shoots of smooth cordgrass, Spartina alternaflora. These mussels are capable of collecting microplankton down to picoplankton size, including bacterioplanktonic cells, from the flooding saltmarsh tidal waters. Their filtration can remove about 30% of bacterial cells and induce about a 25% increase in per-cell bacterial productivity. Photo from old ASLO slide collection; taken by S. Newell; background information provided by S. Newell; scanned by K.L. Schulz.