Wikipedia tells me that there are 422 types of Geraniums. They are mostly found at Eastern Medditeraneum region. It would grown in any soil as long it is waterlogged. So it is no surprise it grows in yours Australia.
Have you know that English word Cranesbill comes from their shape that reminds on fruit capsule on some if their species.
One of the species of it Sticky geranium is protocarnivorous so it is feed by meat.
This is how it looks like so don't put your fingers into it.
All the photos are from Wikipedia.