Archaeocidaris illinoisensis Age: Mississippian Formation: St. Louis Formation Location: St. Louis, Missouri Size: Plate is 2.75 inches across Price:$28.00
This is a very distinct Archaeocidaris illinoisensis from the Mississippian of St. Louis. Fossil echinoids from the St. Louis area are famous around the world and have been extremely sought-after by collectors for decades. These spiny urchins are larger than the Lepidocidaris found in the Mississippian Warsaw Formation, and are OLDER than the Pennsylvanian Archaeocidaris from Texas. This urchin is complete with MANY barbed spines still intact. The echinoid displays well on the large, natural plate of matrix. This is a collectible example of Archaeocidaris from the St. Louis Formation.