Fossilized Ammonite Shell of the Cretaceous Cleoniceras Cleoniceras Ammonite Shell - Red Iridescent - Height: 201 mm - Width: 168 mm- 1800 g - (1)

Spectacular section polished to a ruby opalescence — This specimen represents a carefully polished section of a fossil shell of *Cleoniceras sp.*, an extinct ammonoid cephalopod genus that lived during the Cretaceous period, about 145–66 million years ago. The preparation reveals the complex internal structure of the shell, characterized by a coiled central spiral and a large outer living chamber, typical of the morphology of these ancient marine creatures. The shell's internal matrix has been completely replaced by minerals, a process known as permineralization, which has preserved the finest details of the sutures and the septated chambers. The polished surface of this fossil displays an earthy color palette, ranging from light beige to honey-brown, with smoky gray shading and darker accents outlining the ancient chambers. The luster is heightened by mirror-polish, which captures and reflects light. A distinctive area of iridescence, with tones ranging from fiery red to vivid orange, emerges in one of the inner chambers, mainly visible under direct light. This phenomenon is due to the presence of fossil nacre or secondary mineralogical alterations that have created an optical light-diffraction effect, giving the specimen an exceptional and rare visual quality. The provenance of this *Cleoniceras* is Madagascar, an island globally renowned for the extraordinary preservation and aesthetic beauty of its ammonite fossils. Malagasy Cretaceous deposits are famous for yielding specimens that often show exceptional internal mineralization and, in some cases, phenomena of opalescence or iridescence. This marine-deposition geological context, followed by a slow diagenetic process, has allowed the formation of fossils of such quality and integrity, making them highly desirable for scientific and amateur collection. The specimen’s structural integrity is remarkable, although natural fracture lines and intrinsic color variations from the fossilization process can be observed, attesting to its authenticity and geological history. The form has been preserved with precision that enables detailed study of its evolution and morphological characteristics. The overall appearance is of great visual impact, highlighting the contrast between the shell’s neutral tones and the burst of iridescent color, making it a display piece. This iridescent *Cleoniceras* is not only a piece of natural history but also a work of art created by nature, capturing the essence of prehistoric marine life. Its rarity, due to the combination of significant size and vivid iridescence, makes it a valuable addition to any high-level paleontological collection. It is a fascinating object of study and a highly esteemed decorative item, capable of stimulating scientific curiosity and aesthetic appreciation for the wonders of the planet’s past geology.