The name "Ammonite" originates from the Greek horned ram called Ammon. Ammonites are perhaps the most widely known fossils, bearing typically banded spiral formation shell. These squid-like creatures lived in the sea between 65 - 415 millions years ago.
From the Paleozoic era to the end of the cretaceous era, Ammonites jetted around the world's oceans preying on smaller forms of marine life. For nearly 330 million years, they were abundant in all of the oceans until they suddenly became extinct, around the same time as the demise of the dinosaurs, 65 million years ago.
Ammonites were cephalopods (predatory marine mollusks) similar to the modern Squid, Octopus and chambered Nautilus. Ammonites were able to swim, thanks to the unique construction of their shell, which was divided into a series of air chambers. The air in the chambers provided buoyancy for animal to float, like modern cephalopods, they probably moved through the water using jet propulsion. The Ammonite animal lived in the last chamber of the shell. The rest, the inner chambers, were filled with gas or fluid which was used to control buoyancy and movement.