This small specimen has a 3" long Orthoceras specimen, which has been polished to reveal the inner segmented chambers.
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.
While orthoceras is the common name for these cephalopods, there are actually several different genus including Michelinoceras and Arionoceras found in association. Unless you are one of the world's leading experts on fossil cephalopods you probably won't be able to tell them apart.