This ammonite from Madagascar is a Cleoniceras . It dates back to the Cretaceous, about 120 million years. It is sawn in half and mounted on a rack mechanism with a metalbase. By activating these brass gears, we can discover the complexity of the interior and even calculate its age! It grew from a partition all moon phases: 29.5 days, under optimal conditions. A scientific curiosity... but especially aesthetic!