Ammonites are an incredible and beautiful group of shelled cephalopods that first appeared 400,000,000 years ago. They survived several mass extinction events, including the Permian–Triassic "Great Dying" which wiped out 96% of all marine species.

This necklace is a fossilized shell from an ammonite that has been carefully inlaid with “blue ice” glacierite within the shell chambers. This mineral is a sodium-aluminum oxide from Indonesia, which is produced as a byproduct of industrial smelting. This gives a pop of color to the already incredible fossil pendant.

Each necklace is set into a fine sterling silver backing and comes with an 18" chain. The pendant measures approximately 1" to 1.5" across, though there can be variation depending on the fossil.

The necklace comes in a decorative box and includes a small information card about the fossil. The card serves as the certificate of authenticity and can be found underneath the padded lining of the display box.

ESTIMATED AGE : c. 110,000,000 years old

Ammonites are an extinct group of cephalopods which entered the fossil record 400 million years ago. They survived several mass extinction events, including the Permian–Triassic "Great Dying" which wiped out 96% of all marine species. They finally succumbed during the Cretaceous-Paleogene extinction event 66 million years ago, which also wiped out the dinosaurs.

The size of ammonite shells range from sub-centimeter dwarf species to giants nearly three meters in diameter. Most iconic shells exhibit a nearly perfect logarithmic spiral.

The longevity of ammonites owes itself to their unique anatomy, their soft body parts appearing like a small octopus but protected by a coiling shell.

The ammonite’s body inhabited a large chamber of its shell, with smaller cavities called camerae tapering off as the shell’s coil contracts, the chambers divided by walls called septums. These chambers were filled with gas and fluid and were regulated by a cord called a siphuncle that adjusted levels in the open chambers and thus allowed the ammonite to control its shell’s buoyancy.

With these evolutionary innovations, ammonites were quick swimmers, closing in on prey or fleeing from their own predators, their tough shells protecting them from hunters.

How these creatures lived is of intense interest to science, as ammonites likely played a vital role in the food chain in the ancient seas. Evidence exists to suggest that ammonites were a prime food source for Mosasaurs and fishes, while other studies suggest the bite marks on their remains were created after death by limpets or even by other cephalopods.

Many thousands of distinct species make up the long-lived ammonoid subclass.  Though most ammonite shells are the classic spiral, there are also straight and gastropod-like shells and even some shells that are partially uncoiled.  The surface of the shells also vary quite widely, from smooth to wildly thorny.

Ammonites were an incredibly diverse and plentiful group of animals that survived for hundreds of millions of years and lived all across the planet. Their rapid diversification and tough, rocky shells means there are many different and easily identifiable species in the fossil record. Because of this, scientists can use them to easily identify the age of other fossils and geologic deposits found in the same layer of the ammonites. They're a welcome sight to the eyes of any inquisitive geologist!

Aside from their complex shells, there is little direct evidence regarding the appearance of ammonites due to the absence of soft tissue fossils. However, many scientists believe ammonites had bodies similar to that of the present-day nautilus.

Ammonite shells grew in a natural spiral and made a consistent, mathematically significant pattern. This special shape is known as a logarithmic spiral.

The main property of a logarithmic spiral is that the shape of the spiral is unaltered as it increases in size. Each turn is a pure geometrical progression of the last with a common ratio.  This form is found in many natural phenomena, from the shape of galaxies to patterns on sunflower heads.