Stunning Douvilleiceras Cretaceous Ammonite

Description: This fine ammonite is Douveilliceras mammilatum from Madagascar which has had the original shell removed, allowing you to see how the ammonite’s shell was reinforced with small impact upon its weight, and important factor for an animal which needed to move freely within the water column in pursuit of prey The interior shell is preserved as a cream and green colored Calcite, with the sutures in fine relief. Notice the tubercles present on this example. Members of the genus are found with spines, tubercles, or knobs, and they are thought to be indicative of a hostile environment in which such structures were necessary as a defense. Additionally, you can see the dark line running along the center of the shell. This is the siphuncule, which is what was used by the ammonite to adjust its depth in the water column, much like a submarine. See my other listing for examples of another species.