This is quite unexpected and rather shocking: rock art from Bradshaw, West Australia, keeps no paint all, but remains drawn and visible because of microbes of red and black colors which have colonized the painted area.
This makes dating the paintings almost impossible because they are alive, literally so. However the possibility of indirect dating using DNA sequencing remains open.
The implicated microbes are a black fungus and a red bacteria whose species are yet to be identified but which apparently survive cannibalizing their ancestors.
|Amplified boundary of a a drawing|