Notes on cyanobacteria and photosynthesis
"Cyanobacteria are a phylum of bacteria that obtain their energy through photosynthesis, and are the only photosynthetic prokaryotes able to produce oxygen. The name "cyanobacteria" comes from the color of the bacteria. Cyanobacteria, which are prokaryotes, are also called "blue-green algae", though the term "algae" in modern usage is restricted to eukaryotes." (Wikipedia)
"The Earth is surrounded by a layer of gases which we call the atmosphere. It is the product of photosynthesis, of algae working for millions of years, converting light energy from the sun into air. Evolution’s answer to the atmosphere was the lung. Thus the atmosphere is essential for most living organisms, including people." (/GLOBALE: Infosphere/, https://zkm.de/en/exhibition/2015/09/globale-infosphere)