Ammonite is about 400 million years old. Ammonites became extinct at the same time as did dinosaurs, but many were preserved as fossils. Their only living relative is the pearly nautilus.
These ammonite beads have been opened into halves to reveal the inward beauty and internal chambering of calcite and siderite. The faces of the halves have been polished to further enhance the texture of the ammonite interior.