Hypnotic Gems Gallery: Medium Orthoceras Display Specimens - 8" to 10" Natural Polished Superior Grade Fossils - Collecting, Display Specimen, Curio Cabinets, Fireplace Mantles, Education and Teaching 100% Authentic Polished Orthoceras Fossils Average Size: 8" to 10" These orthoceras are nearly 500 million years old! Each and every fossil is unique and you will receive a piece similar to the image shown! Includes only authentic Hypnotic Gems certified fossils!