This is an impressive, 3.07" long specimen of Crotalocephalus gibbus from Atchana, Morocco. Nice preparation and shell detail. It has been prepared in a "flying" pose by removing nearly all of the surrounding limestone. This leaves it floating above the rock on a pedestal. The preparation takes a lot of time but the results are quite spectacular. It has about 3% shell restoration in total. 
 
Trilobites were a very diverse group of extinct marine arthropods. They first appeared in the fossil record in the Early Cambrian (521 million years ago).