#mussel  marine or freshwater bivalve mollusk that lives attached to rocks etc.
  supertype:  #bivalve__lamellibranch  marine or freshwater mollusks having a soft body with platelike gills enclosed within two shells hinged together
  subtype:  #marine_mussel__mytilid  marine bivalve mollusk having a dark elongated shell; live attached to solid objects especially in intertidal zones
     subtype:  #edible_mussel__Mytilus_edulis  dark-shelled edible mussel that lives attached to rocks
  subtype:  #freshwater_mussel__freshwater_clam  bivalve mollusk abundant in rivers of central United States
     subtype:  #pearly-shelled_mussel  the pearly lining of the dark shells is a source of mother-of-pearl
     subtype:  #thin-shelled_mussel  mussel with thin fragile shells having only rudimentary hinge teeth
     subtype:  #zebra_mussel__zebramussel__Dreissena_polymorpha  inch-long mollusk imported accidentally from Europe; clogs utility inlet pipes and feeds on edible freshwater mussels

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