What are ammonites?
Ammonites were a group of molluscs living in the sea to which the current squid belongs. Nowadays, these animals have their shells inside, but the Ammonites still had their shells outside the body, just like snails. The Ammonite is about 112 million years old and completely fossilised. This specimen has been polished. This makes the stitches that gave chambers strength nicely visible.
Fossilized ammonite from Madagascar
The most beautiful ammonites are found in Madagascar and can have dimensions up to 25 centimeters in diameter. This ammonite belongs to the family of Cleoniceras. In some hollow chambers calcite crystals can be found. These are actually crystal geodes inside the fossil. Ammonites died out about 65 million years ago, just like the dinosaurs.