(Quadrula metanevra) Rafinesque, 1820
A Monkeyface mussel

K.S. Cummings, Illinois Natural History Survey

Other Common Names:
Knobbed rock shell.
Medium to large rivers in gravel or mixed sand and gravel.
Up to 4 inches (10.2 cm).
Outer Shell Color:
Green or light to dark Brown. Usually with zig-zag green lines or V-shaped markings (especially young mussels)
Inner Shell Color:
Pearly white, with iridescent coloring on one end.
Shell Thickness:
Shell Outline:
An outline of the entire shell varies in shape: from almost round to nearly, but not perfectly square (imagine a square blown up, like a balloon). There may be an indentation in the shell outline just to one side of a raised ridge on the outer shell surface.
Shell Surface:
Outer surface is rough: many small pimple-like bumps scattered over most of the shell's surface. The bumps may be larger around a single raised ridgeline that runs from the beak (the point near where the two shell halves connect) to the shell edge farthest away from the beak. There may be a tiny flattened extension of the shell where the two shell halves join.
Scientific Description:
Shell brown, usually with zig-zag green lines (especially young mussels); multiple, large tubercles on posterior ridge. Soft parts colorful. Incurrent papillae aborescent.
Similar Looking Mussels:
Host Fish:
Sauger, sunfishes.
Relatively uncommon but may be locally abundant.
Minnesota State Listing:
Federal Listing:

Did You Know?