This pyrite gastropod fossil has well defined ridges that make it easier to identify. It appears to be a Bellerophon. It was found in a coal mine at a depth of 60-250 meters.
My identification source is Fossils of Ohio (Bulletin 70, Rodney M. Feldmann Editor, State of Ohio, Department of Natural Resources, Division of Geological Survey, Columbus Ohio 1986) pages 162-173, figures 15-16 of specimen from Cambridge shale (Conemaugh Group, Pennsylvanian) New Concord, Guernsey County Ohio, OSU 46696.
The fossil was situated above the coal seam so it might be from the Pennsylvanian Period (late Carboniferous). It was found in Webster County Kentucky USA. The mines there are part of the Eastern Interior Basin. The formations found there are Sturgis, Carbondale, and Tradewater. The limestone layers are Carthage, Madisonville, Providence, Yeargiss?, and Lead Creek.
Learn more about the geology of this area at the United States Geological Survey:
http://pubs.usgs.gov/pp/p1151h/penn.html
