Ammonites are an extinct group of cephalopods that 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. 

This pendant contains a fossilized ammonite shell from Madagascar, estimated to be over 66 million years old. The shell has been split and polished to show the internal chambers of the animal (called septa) along with its natural spiral.

This is both a beautiful treasure from ages long past and a fantastic piece of jewelry. Each pendant is set into a sterling silver ring and 18" chain. Each of these limited-run pendants has been photographed and listed separately, and you can see all pendants in the collection below.

This complete necklace ships in a black jewelry box and anti-tarnish bag, along with an informational card that serves as certificate of authenticity.

Please Note: Each fossil is a unique creature that lived more than 66,700,000 years ago so size and color of the fossil will vary.

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.

Given their abundance in the fossil record, ammonites are often used to estimate the age of the geological layer in which the fossils are found. Their fossils have been found across the world and on every continent, even Antarctica. The fossils in our collection come from Madagascar and lived in the seaway growing between the island and the paleocontinent Gondwana.

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.