Why was the evolution of cyanobacteria such a significant event in earth’s history?

It was a significant event in Earth’s history because the cyanobacteria made the oxygen that we breathe today.

Cyanobacteria is a type of bacteria that is aquatic (lives in the water) and photosynthetic (manufactures their own food). These organisms are usually unicellular, and grow in colonies. Cyanobacteria were particularly important in the development of our planet, as they generated the oxygen atmosphere that we need to survive. This took place during the Archaean and Proterozoic Eras. Cyanobacteria were also very important in the development of plants.

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answer: electrons