Ammonite is a pretty evening dresser with an unusual backstory. She is a fossil because her kind is now extinct. Prized today by jewelry and crystal hoarders, Ammonite once rode the oceans like a stunner until the Cretaceous-Paleogene extinction event some 66 million years ago when three-fourths of the planet’s population was wiped out. Ammonite is a powerful conversation starter. Her name draws from the word “horns of Ammon” referring to her curled horn-like appearance also seen on Egyptian god Ammon.