Cephalopod - Fossil mortality plate - Orthoceras - 14.5 cm (No Reserve Price)

Orthoceras polished to a good size, top quality, very aesthetic.
Paleozoic Era. Devonian Period. 390 million years.
There are large concentrations of these fossils in Erfoud in the Atlas Mountains of Morocco.
They presented an external shell in a conical shape that was divided into chambers which could be emptied or filled with water, thereby controlling buoyancy and allowing it to position at different depths.
When they died, probably in large numbers during mating cycles, their shells accumulated on the seabed, where they were swept away by currents until they settled.