Ammonites are an extinct group of cephalopods that entered the fossil record 400 million years ago. Inside each of their shells was a network of chambers called camerae that were filled with gas, allowing these creatures to control their buoyancy. Coupled with their hydrodynamic shells, ammonites could quickly close the gap between them and their prey.

This fossil ammonite pendant measures 1.570" and has been inlaid with Ethiopian opal, highlighting the fossil's logarithmic spiral and inner structure. The fossil is set into a fine sterling silver backing with an 18" chain.