|Phreatoicideans (order Isopoda; suborder Phreatoicidea)
are found in surface streams (like this isopod from Kakadu NT, Eophreatoicus
Nicholls), in sphagnum swamps, springs and ground waters, in yabbie (crayfish)
burrows, and even burrowing in soil. Phreatoicideans have a fossil record
extending back 325 million years into the Palaeozoic,
with fresh water fossils known from Triassic
age (200mybp) shales of Sydney, NSW. Despite their long history, phreatoicideans
show surprisingly little morphological differentiation.