It’s a trilobite, sure; who didn’t know that it was a trilobite? But congratulations to Dan Coleman for identifying the genus: Flexicalymene.
“Flexicalymene is one of the world’s best-known trilobites,” write David L. Meyer and Richard Arnold Davis in their A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region (2009), “in large measure due to its abundance in Cincinnatian strata.” It is absent, thankfully, from Cincinnatian chili.
And a tip of the pygidium-rolled-up-into-the-cephalon hat to Dan Phelps for the photograph.
