Describe the organism that scientist believe was responsible for changing the composition of the early atmosphere what is it called and how did it change the atmosphere why was this change the atmosphere so important? 75 points

The existence of photosynthetic organisms, particularly the blue-green algae, are the organisms responsible for changing the early atmosphere of the Earth. These organisms came from rock formations found throughout Earth and are responsible for feeding off on the carbon dioxide that was abundant in its atmosphere. As they have learned to feed-off carbon dioxide, they in turn have transformed this compound and produced oxygen. 

Scientists have also proven that rocks and other sediments contained abundant amounts of trapped oxygen. Through time when the rocks have withered and formed into sediments these oxygen gases are released into the air and got trapped within the atmosphere overpowering the levels of carbon dioxide. 

This phenomenon is very important throughout the history of Earth because the Earth became a habitable planet where several species can thrive. This phenomenon has also led to the several geographical changes that the Earth has undergone to because it cooled-down its overall temperature.