This Specimen has been sold.
.5" Detailed Gerastos Trilobite Fossil - Morocco
This is a detailed, .5" long (if outstretched) specimen of the proetid trilobite, Gerastos, collected from Issoumour, Morocco. It's nicely inflated with great shell detail.
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 currently described species, filling nearly every evolutionary niche. Due in large part to a hard exoskeleton (shell), they left an excellent fossil record.