Calymene was a medium-size trilobite.
It was probably a predator and was found in shallow Silurian seas, usually in lagoons or reefs.
It had a semicircular-shaped cephalon (head shield) with three or four distinct 'lobes' that ran laterally along its central head section, known as the glabella.
The glabella itself was bell-shaped, containing small eyes.
There was a variable number of segments (or tergites) in the middle region, the thorax, depending on the species concerned - British specimens, for example, may have up to 19 segments, while those from North American species have only 13.
Its tough exoskeleton, like that found on many post-Cambrian trilobites, was a good defence against predation and also increased its own chances of being preserved in the fossil record.
This has helped to make Calymene one of the most commonly found trilobite genera
from the Middle Ordovician Period.