Ammonite is a common name for a group of extinct marine mollusks with a coiled shell made up of a series of chambers.  Ammonites are members of the cephalopod class, which includes nautilus, squid, octopus, and cuttlefish.  
 
This ammonite shell is about 300 million years old, dating back to between the Silurian Period (435 million to 410 million years ago) and the Jurassic and Cretaceous Periods (175 million to 65 million years ago.)
 
Ammonite fossils are found in sedimentary rock layers of limestone and clay and in clay mineral iron ore. They are an important index fossil because they often link the rock layer in which they are found to specific geological time periods.
 
Enjoy this fine mollusk, measuring between 4 and 5 inches in diameter. Each ammonite is unique and one-of-a-kind and you will receive a strikingly similar fossil with possible variation in color or texture.