Echinorhinus blakei
Middle Miocene
Calvert Formation
Randle Cliff, Calvert County
Maryland, USA

17mm shark tooth. Rare

See: Kent B. W. (2018) The Cartilaginous Fishes (Chimaeras, Sharks, and Rays) of Calvert Cliffs, Maryland, USA, Smithsonian Contributions to Paleobiology 100, 45-160

A great website reference: Echinorhinus blakei