The photo shows a  tooth from the genus Cladodus, that is still partially embeded in the shale.   Notice to the right of the long central cusp there two smaller cusps or points.  The two from the left side were broken off before the discovery of the tooth.

The photo shows a  pair of teeth from the genus Cladodus.  Notice that on the left specimine their is one major central cusp or point and two smaller cusps to the left. On a complete specimen there would have been two more cusps on the right side. 

Teeth of this form are now not believed to be characteristic of a single genus or species. Cladodus mirabilis is thus a "nomen dubium". (no longer considered a correct taxonomy name) 

Approximate Age: 310-312 million years old. 
Location of Discovery: Peabody Coal Co. Marissa Mine - Washington County, Illinois  (All specimens shown on this page.)