This is a fossil dugong rib section that was recovered from the Peace River in the Bone Valley formation of Florida. Unlike most ribs found in the river, this one still has it's nice white coloration and has not been stained black/brown from the tannins in the water. This rib was likely fossilized in a dry area before it washed out into river recently (in relative terms). This piece measures approx. 4.5 inches long and is very solid.
Refer to the photo. The black centimeter cube is shown for scale and is not included. You are purchasing the specimen shown.
(Miocene Period, approx. 7-14 million years old)