Description
Ammonite fossil 8cmx6xm, beautiful crystalised calcite caves, some opalization on backs. Madagascar.
Ammonites are an extinct group of marine molluscs that existed in our oceans from the Devonian period (400 million years ago) till the Cretaceous period (65 million years ago). They belong to the Cephalopod class which contains squids, cuttlefish, octopus and nautilus.
The shells of ammonites are made up of many segmented chambers separated by a wall called the ‘Septa’. The chambers were connected to one another and the body of the animal by a tube called a ‘Siphuncle’. The siphuncle is used to adjust buoyancy and change the animals’ position up and down in the water column.
The hard shells of ammonites have allowed for excellent preservation as fossils, they can be used as an indicator to the locations of our ancient seas.
