A cross section of pyritized fossil ammonite shell in a nautilus spiral, set in silver and hung on a short adjustable silver chain. Pyritized fossils are the result of a fossil forming inside a natural deposit of the mineral pyrite. As the fossil forms the natural calcium shell is replaced with the nearby pyrite material.

This piece is reversible, one side displays the smooth polished cross section of pyrite in the spiral shape of the shell and the other is the natural surface of the shell fossil with a slight rainbow iridescence.