This is one of those trilobite specimens that makes you say, "wow they really do look like little aliens". It's a fantastically prepared Crotalocephalina gibbus from Atchana, Morocco. What makes this particular specimen so special is it was prepared in a "flying" pose by removing most of the rock from underneath so that it is perched on a pedestal. Even much of the matrix was removed from underneath all of the pleural spines. This would have taken DOZENS of hours of preparation work by a very skilled preparator under microscope.
The trilobite itself is 3" long and is perched high atop a limestone base that displays nicely on a flat surface.
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) and went extinct during the Permian mass extinction (250 million years ago). They were one of the most successful of the early animals on our planet with over 25k described species, filling nearly every evolutionary niche. Due in large part to a hard exoskeleton (shell), they left a excellent fossil record.