Answer: Flutedshell mussel, Lasmigona costata
This beautifully colored shell belongs to a local fresh-water mussel species, Lasmigona costata, or Flutedshell. Scientists can use its coloration to infer the age of the individual. Sand mussels live in medium to large rivers and although they are found all over the Midwest, these mollusks are uncommon. The specimen you see here was collected in Illinois in 1897; such specimens help us document where species have historically lived in the event that pollution or other environmental factors affect their habitats.