Aboriginal rock painting at Ubirr, Kakadu National Park. This rock painting depicts a 'dream-time' story of two sisters, the Namarkan sisters, who could turn into crocodiles (and back into humans) at will. They could then play tricks on people, scaring them out of their wits. Unfortunately, they then stayed crocodiles. Their spirit is in each crocodile, giving the crocodiles a mischievous glint in their eyes. Their spirits can also reach into people with something like strings, causing illness.