Seashells That Became Gemstones

Ammonites were prehistoric ocean-dwelling shelled creatures whose fossil remains are everywhere. In some locales, the fossils have done something very unique.. they became gorgeous iridescent gemstones!

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Ammonites in paleontology are an extinct group of marine animals whose closest relatives today is probably the subclass Coleoidea, which include the squid, octopus and cuttlefish. They had protective spiral shells about them and despite a striking resemblance to the modern day Nautilus, they are unrelated. The shape their shells were usually either of plainspiral or helically-spiraled, and even some non-spiraled (more like a ‘cone’.) The common ram’s horn shape is rather familiar as in this stylized street lamp adornment, above.

Ammonites came in many varied sizes and shapes.

Near Pompeii in 79 A.D., the Greek Pliny the Elder called these fossils “ammonis cornua” meaning “the horns of Ammon.” Ammon was the Egyptian god typically depicted wearing the horns of a ram.

Ammonite fossils are considered to be great ‘index fossils’ as it is possible to relate specific geological time periods to the strata of rock layer that they are embedded in. An “index fossil” pertains to the faunal stages of different sediments that even though they might appear different depending upon whatever conditions existed when they were deposited; they include remains of the same specie of fossil. This can be particularly useful when the specie’s reign was of a shorter duration (say, a few hundred thousand years,) or, became extinct within a fairly abruptly by such a short time determined to be a period beginning widespread environmental changes (regional drought, flood, volcanism, etc.) that is verifiable by other means.

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Some ammonites are not just fossilized, they become ‘pyritized’, their mass is replaced with pyrite. I have seen other such fossils, specifically, from Pennsylvania USA that have such a naturally occurring treatment. Collectors at Trade Shows often have nice specimens of these to sell and trade. I even have a small ammonite in my own private collection of objet trouvé although, not a pyritized specimen.

Closeup of a Ammonite Fossil

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Under certain exacting and still unexplained conditions, Ammonite fossils have transformed during fossilization into something truly unique. Their ‘mother of pearl’ interior layer was mysteriously preserved in the fossil record and given unusual properties of light refraction, causing myriads of rainbow colors when polished. Such a place where this has occurred is in the Black Bearpaw Shales of southern Alberta Province, Canada. These fossilized precious gemstones are being turned into stunning works of Ammonite jewellery.

Ammonite Jewelery and an Example Source Specimen of This Gemstone

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The life cycle of the living Ammonites can only be guessed at but it is believed that they swam in the open ocean and were not ‘bottom dwellers’ as their fossils are often found in large quantities in strata devoid of any other fossilized forms. This suggests that they when they died, they sank to the barren ocean floor to eventually become fossilized in the silty layers. Had they been ‘bottom dwellers’, their fossilized remains would likely have also been found along with whatever they preyed upon. -They would have been discovered to have died in a more favorable ecosystem, one that would have supported their life needs. The modern analogy is like the herds of wildebeest that attempt to swim across raging rivers in Africa and drown, sometimes in large numbers, and their dead bodies drift to a sandbar downstream where they aggregate in large numbers. That is not where they had lived, but it is where they finally came to rest. These places are the fossil beds of the distant future.

The male Ammonite (called “intercalare”) probably lived solitary lives, as these fossilized specimens are found singly. The female Ammonite (called “meeki”) probably had a reproductive behavior that included grouping together after spawning, as their fossils are often found in large localized areas. Possibly the females, like spawning salmon, died shortly after giving birth and thus formed these large localized fossil beds. It is the female Ammonite that produce the best iridescent mother-of-pearl gemstone. The males were less colorful, almost bland.

What If They Were Still Alive Today, Somewhere?

Wouldn’t it be a wonderful thing if living Ammonites were discovered in the depths of the oceans today? Although, it is possible that if found as a creature still living today, they would become an exploitable resource due to their enormous size and their mother-of-pearl inner shell. Perhaps though, if the theory is correct that the females congregated and died naturally shortly after spawning, there might be an Ammonite equivalent of the fictional ‘elephant’s graveyard‘ of decedent shells, commercially available at no detriment to the cryptic living creatures. Oh, one could wish!

As a living fossil, cryptozoologists would love very much to discover living Ammonites. As would anyone whom fancies the beautiful jewelry that these now extinct ocean-dwelling creatures left behnd.