This is a fossil ear bone (periotic bulla) from a small cetacean species. It was recovered from a gravel bar in Florida's Peace River (DeSoto County, Bone Valley Formation). This bone likely belongs to a small, extinct, river dolphin (Pomatodelphis inaequalis) or Squalodelphinid sp. It is in excellent condition and well mineralized.
Refer to the photos. The black centimeter cube is shown for scale and is not included. You are purchasing the specimen shown. Your purchase will include an ID label.