Approximately 500 -190 million years old. 

Orthocears fossil are squids from the Sahara; in these shells lived orthoceras, an ancient mollusk whose fossil shells are found and polished in the Sahara Desert of Morocco. In the Devonian geologic period, some 350 million years ago, these ocean dwellers, reaching a length of up to 6 feet, swam in an ocean which covered the area. After death, their shells were preserved in the black marble where they are found today. They moved by ejecting water through an opening and by moving their tentacles. The tentacles caught food while their parrot-shaped beaks cut the food up. The towers are freestanding, with each fossil section beautifully polished and some of the orthoceras fossils have nice crystallized chambers.