Perisphinctes Ammonites
Perisphinctes Ammonites quality specimens in many sizes. These ammonites are from Sakaraha, Madagascar 1 inch and up. Perisphinctes is an extinct genus of cephalopod that lived during the Jurassic Period. They are commonly white to tan in color. The shell has characteristic ridges that spiral around the outside surface of the shell. 
Like all ammonites, Perisphinctes was a predator. This genus has been found in many locations around the world. Because of its abundance and widespread distribution it is used as an index fossil.
