This is a fossil Cyrtina that I received in a large lot of fossil material from an old collection. It had a label with it that stated the fossil was from the Genshaw formation near Alpena, Michigan. Based on my searches for Cyrtina sp. from the Genshaw formation on the Friends of the University of Michigan Museum of Paleontology website (HERE or a slightly easier interface HERE), I think this is a Cyrtina umbonata.
The Genshaw formation is part of the Traverse Group which is late Givetian stage within the middle Devonian.