2.8" Fossil Echinoid (Archaeocidaris) - Missouri
This is a 2.8" fossil echinoid from the St. Louis Limestone in Missouri. The quality of preparation on this fossil is exquisite - using skillful air-abrasion techniques under a stereo microscope.
Sea urchins are a type of echinoderm which are still living relatively unchanged today. They live at the bottom of soft ocean floors and have long spines protruding from their central body. They move along the bottom of the ocean using many small feet while feeding on various plant and animal matter.