Rainbow Iridescent Cleoniceras Ammonite Natural Fossilized Shell - Height: 119 mm - Width: 102 mm- 401 g - (1)

A specimen with a mother-of-pearl, paleopal iridescent shell preserved — We present a remarkable fossil ammonite of the genus Cleoniceras, from the famous Madagascar deposits. This fossil, dating to the Early Cretaceous, is distinguished by the spectacular preservation of its outer shell in mother-of-pearl, which displays an intense and vibrant iridescence. The specimen immediately catches the eye thanks to its chromatic play, turning a paleontological find into a true natural gem. The ammonite develops in a classic logarithmic spiral, an iconic form of nature’s geometric perfection. The photographs document the surface accurately, where large portions of the original shell have been preserved. Under light, this surface comes alive with flashes of color ranging from emerald green to golden yellow, from vivid pink to peacock blue. This phenomenon, known as opalescence or “fire,” is due to the diffraction of light through the microscopic layers of aragonite that make up the mother-of-pearl. You can also observe the thin sutural lines, typical of the genus Cleoniceras, glimpsing beneath the iridescent surface, adding complexity and scientific interest. The fractures visible on the shell are not defects but authentic testimonies of the long and complex fossilization process that lasted millions of years. The extraordinary iridescence of this fossil is not an artificial alteration, but a rare and precious taphonomic characteristic. During fossilization, the aragonite shell of the mother-of-pearl managed to remain intact, without recrystallizing into calcite (a more stable mineral but non-iridescent). This exceptional preservation process is typical of some Cretaceous marine deposits in Madagascar, which allowed these ancient cephalopods to reach us in all their original chromatic splendor. The visual effect is comparable to that of the most precious organic gems, such as noble opal or pearl. Ammonites of the genus Cleoniceras thrived in the oceans about 110 million years ago, during the Albian stage of the Early Cretaceous. They were marine predators with an external shell divided into chambers, which they could fill or empty with gas to control their buoyancy, in a manner similar to the modern Nautilus. At the time of their death, the shells settled on the seafloor, where they were buried by sediments. Over eons, minerals present in the environment mineralized the structure, turning it into a durable fossil that preserved its shape and, in fortunate cases like this, its surface microstructure. This Cleoniceras specimen represents a highly valuable addition to any natural history collection. It is not only a scientific document of life past but also an object of undeniable aesthetic beauty. Its generous size and exceptional chromaticism make it a perfect display piece, ideal for enriching a modern Wunderkammer, a professional studio, or a library. Its ability to interact with light makes it a dynamic and fascinating focal point, a silent dialogue between Nature’s geometry and the physics of light, enclosed in a fragment of deep time.