Ammonites are among the most beautiful fossils with their coiled shells. They are a subgenus of the Cephalopda squids). They were shellfish that were found in very large numbers in the last Paleozoic and throughout the Mesozoic. They are found as fossils.
The shell is usually made of Aragonite. Where the shell has been preserved, layers of mother-of-pearl can provide a special color palette. Small ammonites are often found in pyritised form.
Ammonites are most closely related to the squids. These animals probably had ten arms. Ammonites came in hundreds of varieties and species. They almost all have the same floor plan: a flat spiral shell.