Phreatoicidea is a suborder of isopodcrustaceans. Extant species are confined to freshwater environments in South Africa, India, and Oceania.[2] This seemingly Gondwana-derived distribution belies the fact that the group once had a cosmopolitan distribution; fossils which can be assigned to the Phreatoicidea are the oldest isopod fossils, and are found throughout the world.[3][4] In the intervening 325 million years, phreatoicideans have changed little, and are thus considered living fossils.[5]