Scaleshell, MAL-19741 View of one half of shell.

The scaleshell (Leptodea leptodon) is a critically imperiled freshwater mollusk. The stream where this specimen was collected in 1903 no longer supports any populations of the species, and in fact the only surviving populations are found in a mere 14 streams! Scaleshells, like many other species in the family Unionidae, are indicators of water quality. Unionid populations across the midwest have experienced sharp declines due to industrial pollution and other habitat degradation in the past century.