This is a Orthoceras Fossil segment with has been polished to reveal the remarkable fossilization and drilled to be worn as a pendant.
Orthoceras is a genus of extinct nautiloid cephalopod. Orthoceras fossils are dated back more than 400 million years ago and are ancestors to the modern day Squid and Octopus. As they died their shells accumulated upon the ocean floor, covered slowly by sediments they transformed into stone over the ages. Orthoceras fossils have been found to occur in any marine rock, especially limestones and have a wide global distribution. This particular specimen was sourced from Morocco.