Question

billion years ago. this evidence was found in fossilized which were formed by layers of also called blue - green algae. these first life forms were microbes that used carbon dioxide, water, and sunlight to produce food and. it took millions of years for earths atmosphere to build up oxygen, and primitive primordial soup became the. as the lava cooled and hardened, both oceanic and continental formed. oxygen oceans photosynthetic cyanobacteria stromatolites

Explanation:

Stromatolites are fossilized structures formed by layers of cyanobacteria (blue - green algae). Photosynthetic microbes like cyanobacteria use carbon dioxide, water, and sunlight to produce food and oxygen. Primitive primordial soup evolved into oceans over time. As lava cooled, oceanic and continental crust formed.

Answer:

1. stromatolites
2. cyanobacteria
3. photosynthetic
4. oxygen
5. oceans
6. crust