Round plate or bowl made of prehistoric fossils. Ammonite and Orthoceras art

This plate is carved out of volcanic ash that covered these ancient sea animals. And was fossilized under the pressure of the ocean over millions of years. It is around 12 inches wide, and 1/4 inch thick. Orthoceras: These very primitive members of the phylum Cephalopoda are similar to the ammonites, with a straight shell. Approximately 400, 000, 000 years old, orthoceras are the ancestral cousin of the modern-day squid or octopus. The word orthoceras means " Straight Horn", and refers to its shape. All orthoceras have chambers separated by walls called septa. They also have a tube that runs down the center of the fossil called a Siphuncle. It is believed that this tube was used to carry gas into the chambers to control the buoyancy of the shell. The Orthoceras from Morocco occurs as white fossils in a dark grey or black marble matrix. The result is a fossil with very good contrast. This probably is the best selling of the Moroccan fossils. Ammonite: The word Ammonite is derived from t