This is a very nice, high quality Ammonite Sphenodiscus in matrix from the Fox Hills Formation in South Dakota.  The Sphenodiscus measures nearly 2 1/2″ x over 2 1/4″ in a fossilized matrix measuring nearly 4 1/4″ x over 4″ x 3 3/8″.  The Sphenodiscus has a natural, iridescent, pearl-like finish.  These fossils make great gifts or work wonderful as an educational tool for school, scouts or clubs. Close observation will reveal several other partial to semi-complete fossils throughout the matrix.