Ammonite Shell Fossil

These marine mollusks existed throughout the Mesozoic Era, which is an interval of geological time from about 252 to 66 million years ago.  This fossil is 4" wide and 3 1/4" long.  It is cut in half and polished to show the inside sections, called "Septa".  The other side is raw and shows the texture of the outside of the shell.  This is a fossil, so all organic material has been replaced by rock over time, this rock appears to be agate and crystal.