Claim: The extinct Aenigmacaris are classified in the Arthropoda phylum and their closest relatives are the mantis shrimp.
Evidence: Aenigmacaris is an extinct genus of malacostracan crustacean, which includes the species Aenigmacaris cornigerum and Aenigmacaris minima. Arthropoda Phylum: Their closest extant relatives are the mantis shrimp.