Stromatolites at Shark Bay, Western Australia. Image by C Eeckhout (Wikimedia Commons).Photosynthesis is great. Plants (and some bacteria) use some CO₂, some H₂O, and a bit of sunlight to build themselves. The sunlight involved is mainly within the visible range of the electromagnetic spectrum, especially around 430 nanometres (violet) and 660 nanometres (red). When I say “some bacteria”, I refer to cyanobacteria. These fabulous organisms are believed to have triggered a huge boost in early biodiversity when they started photosynthesising (about 3.5 billion years ago), absorbing CO₂ and releasing O₂. It looks like these guys have been keeping a pretty special secret. More . . .