Oldies But Goodies

This week's PhotoHunt theme is one.

If you are wondering how this picture represents one, your have to go beyond counting the thrombolites, and look at the cell structure of these pre-historic living rocks. Scientist believe that the one celled organism is the earliest form of life on earth, and they date back about 3500 million years.  These relics are mostly extinct and exist only as fossils, but living examples can still be found growing a handful of places in the world. These oldies were photographed at Lake Clifton, 100km south of Perth.