can you name any organism of this taxon whose fossil has been discovered?
Yes, "Canadaspis" and "Perspicaris".
Crustacean
Crustaceans have a rich and extensive fossil record, which begins with animals such as "Canadaspis" and "Perspicaris" from the Middle Cambrian age Burgess Shale.
crustacea and hexapoda have what features in common It is now well accepted that the crustacean group is paraphyletic, and comprises all animals in the clade Pancrustacea other than hexapods. what is the first group that you are talking about? It forms a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, shrimps, prawns, krill, woodlice, and barnacles. can you describe their body? It is composed of segments, which are grouped into three regions: the "cephalon" or head, the "pereon" or thorax, and the "pleon" or abdomen. and where do they generally live? Majority live in either marine or freshwater environments. have their fossils been found? Yes, they have a rich and extensive fossil record.
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Crustacean [SEP] Fossil record
Crustaceans have a rich and extensive fossil record, which begins with animals such as "Canadaspis" and "Perspicaris" from the Middle Cambrian age Burgess Shale. Most of the major groups of crustaceans appear in the fossil record before the end of the Cambrian, namely the Branchiopoda, Maxillopoda (including barnacles and tongue worms) and Malacostraca; there is some debate as to whether or not Cambrian animals assigned to Ostracoda are truly ostracods, which would otherwise start in the Ordovician. The only classes to appear later are the Cephalocarida, which have no fossil record, and the Remipedia, which were first described from the fossil "Tesnusocaris goldichi", but do not appear until the Carboniferous.