Waldron Shale brachiopod found in Clark County, Indiana.  The creature existed in the Middle Silurian Period.  My best guess as to its id...

The Melonites multipora sea urchin fossil found in St. Louis, Missouri.  The creature existed in the Mississippian Period.  It was on dis...

Ammonite fossils of the Promicroceras planicosta on display at the Smithsonian Museum of Natural History in Washington D.C., USA.  Rock ...