> most oxygen (50-80%) is created by phytoplankton in the ocean. True, but not the whole story. Phytoplankton did not create Earth's oxygen atmosphere but toda

> most oxygen (50-80%) is created by phytoplankton in the ocean. True, but not the whole story. Phytoplankton did not create Earth's oxygen atmosphere but today is the majority producer of oxygen. Earth's oxygen atmosphere was initially created by cyanobacteria up to 3.5Bya and which today still produce about 10% of atmospheric oxygen. The detail I am unsure of is what produced most of the current volume of Earth's oxygen. While phytoplankton today produces the most, that does not mean that most of Earth's oxygen was created by phytoplankton. My suspicion is that, though today cyanobacteria does not produce the majority of oxygen, that cyanobacteria in fact created most of the oxygen currently in our atmosphere. Surely someone here knows for certain and can speculate on whether the idea of installing cyanobacteria on Mars is any good.