See how it all began (but please don't visit!) Answered
A news article on Nature today reports a find of living, growing stromatolites in an Andean saline lake (first image). Stromatolites are layered growths of cyanobacteria (photosynthesizing algae), and constitute some of the oldest (3.5 Gya!) macroscopic fossils known (second image).
Update: My writeup above might be a bit misleading. This is not the only known stromatolite colony; Shark Bay, Australia, is the most well known, and there are a few in South Africa. This discovery is important both because of the altitude, and because it's an inland site without contamination.
Note: If you don't understand some of the words above, open a new browser window, type "wikipedia" in the search bar, then cut and paste the big words into Wikipedia.