unknown crustacean
Identified as Phreatoicidea on Bowerbird by Zac Billingham: "Hi Reiner, great sighting. This is a Phreatoicidean Isopod. They are rarely encountered and are quite easily mistaken for Amphipods. Unlike most other Isopods they have a laterally compressed body form, giving them their similarity to the Amphipods. Phreatoicidean Isopods are most easily distinguished from Amphipods by examining the terminal appendages and counting the number of uropods - 1 pair in the Phreatoicideans and 3 pairs in the Amphipods (though some families such as Chiltoniidae and Talitridae show reduction in the 3rd pair of uropods and can look as if they lack the 3rd pair). There are several species of Phreatoicidean thought to be endemic to the grampians, including one which can grow to several centimetres in size and are quite remarkable."