Asaphellus sp. and Aegirocassis benmoulai
Ordovician
Fezouata Formation
Mecissi-Zagora Region, Draa Valley, Morocco.

Huge 145mm (5.7 inch) trilobite with 140mm (5.5 inch) anomalcaridid appendage on big 287mm (11.2 inch) slab. Very unusual combination. Only specimen like this we have ever seen.

Arthropod. Trilobite. Soft-bodied. Lagerstatte. Lagerstatten. Association.

Asaphellus is a genus of trilobite known from the Ordovician of Argentina, China, and Morocco.

Aegirocassis is a genus of anomalocaridid known only from the Early Ordovician of Morocco.  It was one of the largest of all arthropods that ever lived, reaching about 6 1/2 feet long – almost certainly the largest animal of its time.  Like the largest animal of our time, the blue whale, it has been determined to have been a filter-feeder that descended from predatory ancestors.

Here’s an interesting piece for the fossil association collector.