Tylocidaris clavigera

Tylocidaris clavigera (Mantell, 1822) cast of a sea urchin fossil found in England.  The creature existed in the Cretaceous Period.  Cast on display at the Smithsonian National Museum of Natural History.

Stereocidaris hemigranosus

Stereocidaris hemigranosus sea urchin fossil on display at the Smithsonian National Museum of Natural History in Washington, DC.  The fossil is from Texas and existed in the Cretaceous Period.

Macrocrinus Crinioid with Metablastus Blastoid

On the right is a Macrocrinus mundulus crinoid with its stem, calyx and anal tube intact.  The fossil on the left is an intact blastoid called Metablastus wachsmuthi.  These creatures existed in the Mississippian Period.  The fossils were found in Indian Creek, Indiana.  They are on display at the Smithsonian National Museum of Natural History.  Alex Fabian of Temperance, Michigan loaned the fossils for display.