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Ammonite - - American Museum of Natural History


This is the Ammonite shell of a marine animal that went extinct about 65 million years ago. The shell colourisation is only found in ammonites from Alberta, Canada. Originally the ammonite shell was made of aragonite, which is the same material as which pearls are made. Over millions of years, this animal shell was subject to significant temperatures and pressures and was transformed into a gemstone. It was recognised as a gemstone in 1981 by the World Jewelry Confederation and named Ammolite. Only three types of gems are made by living organisms, this one plus amber and pearls.

The name “ammonite” was inspired by the spiral shape of their fossilised shells, which resemble tightly-coiled rams’ horns. Pliny the Elder (d. 79 AD) called these fossils “horns of Ammon” because the Egyptian god Ammon was typically depicted wearing ram’s horns. Ammonoids are an extinct group of marine mollusc animals and are more closely related to octopuses, squid, and cuttlefish.

In medieval Europe, fossilised ammonites were thought to be petrified coiled snakes, and were called “snakestones” or “serpentstones”. They were considered to be evidence for miracles by saints and were held to have healing or prophetic powers. Traders would sometimes carve the head of a snake onto the ammonite fossil or merely paint it on and sell them as petrified snakes.

Ammonites from the Gandaki river in Nepal are known as saligrams, and are believed by Hindus to be a concrete manifestation of God.


  • Title:                   Ammonite
  • Date:                   65 million years ago
  • Place:                  Alberta, Canada
  • Material:            Marine fossils transformed into a gemstone
  • Museum:            American Museum of Natural History


“Isn’t it astonishing that all these secrets have been preserved for so many years just so we could discover them!”
– Orville Wright


Photo Credit: By Joyofmuseums (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons