Mississippian Sea Urchins (Archaeocidaris) - St. Louis, Missouri

This is a piece of limestone from the Mississipian aged St. Louis Limestone of Missouri containing several Archaeocidaris wortheni echinoderms (urchins). The limestone is 5.1" by 3.6" wide and the long spines of these large urchins can clearly be seen on the surface.

It comes with an acrylic display stand.