Natural Harpocreas and Dactylioceras fossil in Poseidonia Shale from Holzmaden Germany- Harpoceras and Dactylioceras are distinct highly sought-after genera of Early Jurassic ammonites, frequently found preserved together in the Posidonia Shale of Germany and the Yorkshire coast of the UK, dating back approximately 180 million years, these fossils are prized for their distinct shapes and striking pyritization (fossil replacement by fool's gold), Harpoceras: known for its compressed, sleek, and aerodynamic shape featuring a sharp, distinct keel and fine, curved, sickle-like ribbing; Dactylioceras: recognizable by its more robust, openly coiled shell, famous for its distinct, bold, and straight ribbing that wraps entirely around the whorls, resembling a tightly coiled rope; Holzmaden, Germany: famous for the Posidonia Shale, this region produces stunning, flat-compressed, and often pyritized specimens of both Harpoceras and Dactylioceras, label in German and hanging hook on back, 17” long