An oval shaped semi precious gemstone brown fossil Turritella Agate designer cabochon that is 48 mm by 27 mm and 5.5 mm thick.
Turritella Agate is actually seashell that has been agatized or replaced by silica.
Although people have called this material Turritella Agate for several decades, the name is actually incorrect. It was mistakenly named after a genus of fossil snails that are very similar to the shells in the agate. The proper name of the snails is "Elimia tenera," a member of the Pleuroceridae family.
This unique fossil gemstone material comes from the Green River Formation near Wamsutter, Wyoming.
Turritella Agate is from the Miocene Epoch and is about 24 million years old.
Turritella fossil cabochons are about a 7 hardness, wear well and take a good polish.