The fossils commonly known as orthoceras are extinct "straight" cephalopods that lived during the Upper Devonian period around 370 million years ago. Like other cephalopods they lived inside of their shell, had tentacles they could use to grab food and used jet propulsion, squirting water to move. The rock containing them is quarried from the Atlas Mountains of Morocco and frequently polished to make decorative items with the fossils visible on the polished surface.