GENERAL KNOWLEDGE

Detailed explanation-1: -These organisms, blue-green algae (picture of stromatolite, which is the rock formed by these algae), fed off atmospheric carbon dioxide and converted much of it into marine sediments consisting of the shells of sea creatures.

Detailed explanation-2: -Stromatolites photosynthesise, they use the sun’s energy to make food. As the stromatolites absorb sunlight they are able to break the chemical bonds in water releasing oxygen.

Detailed explanation-3: -“The microbial mats that created them were predominantly made up of cyanobacteria, which used photosynthesis – like plants do – to turn sunlight into energy, while producing so much oxygen over time they changed the early Earth’s atmosphere to make it habitable for complex life.

Detailed explanation-4: -Early cyanobacteria in stromatolites are thought to be responsible for increasing the amount of oxygen in the primeval Earth’s atmosphere through their continuing photosynthesis. They were the first known organisms to photosynthesize and produce free oxygen.