This is a fossilized "ankle bone" (navicular) from an extinct Pleistocene horse species (Equus sp.). It was recovered from Florida's Peace River in the Bone Valley Formation (Hardee County). It is approx. 12,000 to 2,500,000 years old and is in excellent condition. I was initially stumped on the ID for this odd-shaped bone, so I contacted a professional paleontologist to have it authoritatively identified.
Refer to the photos. The black centimeter cube is shown for scale and is not included. You are purchasing the bone shown. Your purchase will include an ID label.