The Anomalocaridids comprise a group of very early marine animals known primarily from fossils found in Cambrian deposits in China, United States, Canada, Poland and Australia. They were long thought to be restricted to this Cambrian time range, but the discovery of large Ordovician specimens has extended this somewhat. The later Devonian Schinderhannes shows many anomalocaridid features. Although originally interpreted as an anomalocaridid-like arthropod, some recent studies suggest that it may represent an anomalocaridid: if so it would extend the group's record by some hundred million years: the non-mineralised anomalocaridid structure means they are absent from the intermediate fossil record.

We present here some amazing specimens or parts of them that correspond to the Lagerstatte of the Fezouata Formation (Lower Ordovician). Among them, a very curious type of anomalocaridid, with filter-feeding. They have filtering appendages in the form of a comb. The species is: Aegirocassis benmoulai, Van Roy & Briggs (2011).