The Proetus trilobite lived in the Devonian period, between 345 million and 435 million years ago. The trilobite is the first creature known to have eyes, some believe they had 360-degree vision. the first creature known to have eyes, some believe they had 360-degree vision.
Like other trilobites, the creature is made up of three different parts: the cephalon (head), the thorax (body), and the pygidium (tail). The creature was protected by a hard calcite shell and this is what remains fossilized to this day. This shell would not grow with the creature, so the shell wall molted several times during the creature's lifetime. Thus, one trilobite may have left several fossils during its lifetime.