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

A specimen with an opalescent mother-of-pearl shell preserved — We present a remarkable fossil ammonite specimen belonging to the genus Cleoniceras, from the famous Madagascar deposits. This fossil, dating to the Early Cretaceous, stands out for the spectacular preservation of its external shell in mother-of-pearl, displaying an intense and vibrant iridescence. The specimen immediately captivates the eye with its chromatic play, turning a paleontological relic 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 bright 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 intricate fossilization process that lasted millions of years. The extraordinary iridescence of this fossil is not artificial alteration, but a rare and valuable taphonomic feature. During fossilization, the aragonitic shell of the mother-of-pearl managed to remain intact, without recrystallizing into calcite (a more stable but non-iridescent mineral). 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 finest organic gems, such as noble opal or pearl. The Cleoniceras ammonites thrived in the oceans about 110 million years ago, during the Albian stage of the Early Cretaceous. They were marine predators with an outer shell divided into chambers that could be filled or emptied of gas to control their buoyancy, in a manner similar to the modern Nautilus. At the time of their death, the shells settled on the seabed, where they were buried by sediments. Over eons, minerals 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 precious addition to any natural history collection. It is not only a scientific document of past life but also an object of undeniable aesthetic beauty. Its generous size and exceptional colorfulness make it a perfect display piece, ideal for enriching a modern Wunderkammer, a professional study, or a library. Its capacity to interact with light makes it a dynamic and fascinating focal point, a silent dialogue between the geometry of nature and the physics of light, housed in a fragment of deep time.