Cleoniceras

Hailing from the island nation of Madagascar is this cut and polished Cleoniceras Ammonite. The creature which once inhabited this shell died about 105 million years ago during the Albian stage of the lower Cretaceous. Note the pearlescent exterior of the shell and the hollow interior of the chambers. This specimen was not terribly expensive and the fossils are extremely common at many fossil dealers tables or websites.





I liked this specimen because of the exterior shell being intact. Some specimens are ground and polished so that you can see the suture lines of the chambers where they met the exterior shell. It also clearly displays the typical growth pattern of coiled Cephalopods with a spiral of previously occupied chambers winding back to the beginning of the creatures life. I wonder how often the animal would pull it's body forward and seal off another section of it's shell to be used for buoyancy? I can count more than sixty chambers but there are probably more that I can't discern because they are too small. If they made a new chamber every month then this animal would be at least five years old, but this is only speculation.