“Turritella jasper” is a widely known ornamental stone, but its name is misleading. Rather than marine Turritella shells, it contains freshwater gastropods of the genus Elimia. Formed during the Eocene in the Green River Formation, this material is a fossiliferous chalcedony created through secondary silicification. Its dense fossil content and unique textures make it highly valued in lapidary work, bridging the gap between scientific understanding and commercial terminology.