Ammonites are fossils of squid-like mollusks. They lived in the oceans between the Devonian (± 400 million years ago) and the Mesozoic (± 65 million years ago). Especially during the Jurassic and Cretaceous periods - ±200 million to ±65 million years ago - they populated the seas in large numbers.
The shell of ammonites is spiral-shaped and often has grooves. They can vary considerably in size: from a few centimeters to even meters in diameter. On the inside, the shells consist of thin walls, also called septa . On the outside of the shell you see lines where these septa are located inside. These lines are called sutures .
Here you see the septa (thin walls in the shell).
Just like squidsAmmonites could "swim" using their ink sac, just like today's squids. They belong to the class Cephalopoda, just like squids and octopuses, meaning they are genetically related. Their shells may have helped regulate their buoyancy and stability in the water.
Ammonite (Acanthoceras) from Cap Blanc Nez in France.
Polished ammonite from North Africa.
The ammonites from Rootz GalleryPolished ammonite from North Africa.
Rootz Gallery has a large collection of fossils. You can always email us if you are looking for a specific type of fossil, shell, or gemstone. All photos used in this article are of items from our collection.
Part of our collection of ammonites.
On our website you will find ammonites from England, France, and North Africa. These include polished ammonites and rough ammonites.
Ammonite (Liparoceras) from England.
