Wikipedia
Fenestraspis
Fenestraspis is an extinct genus of trilobite in the order Phacopida from the Upper Pragian and Lower Emsian. Fenestraspis is unusual because of the development of extensive fenestrae in the posterior part of the body and apparently of the thorax, the presence of upwardly directed spines on the cephalon, thorax and pygidium, and the exceptionally large and highly elevated eyes.