Saw this big monster in a creek last night along with a heap of its smaller brethren.
It's the Sydney Crayfish, Euastacus australasiensis. Wouldn't want to try to pick that guy up, even if I avoided those nasty claws there are still those painful looking spikes to contend with. Truly a well defended beast.
Close inspection pays off as usual, you can see those funny looking oval things on its carapace and claws - zoom in on the photo and what do you see?
Temnocephalans of course.