Sourced from the remote Mustang District of Nepal, these Ammonite Nodules are premier geological specimens from the Jurassic Era. Dating back approximately 160 million years (Oxfordian stage), these fossils originated in the prehistoric Tethys Sea. Tectonic forces eventually transitioned these marine remains from the ocean floor to the high-altitude riverbeds of the Himalayas. Each nodule features a smooth, water-worn patina sculpted by centuries of river erosion. When opened, they reveal the distinct logarithmic spirals and complex suture patterns of the ancient cephalopods. Geological Period: Late Jurassic ~160 Million Years Ago Composition: Dark Siltstone / Calcified Concretions Locality: Kali Gandaki River, Mustang, Nepal