The first life on earth was born in the primitive ocean 3.5 billion years ago. It is blue algae. Cyanobacteria, also known as cyanobacteria and blue-green algae, are unicellular organisms (organisms with only one cell) and prokaryotes (organisms composed of prokaryotes).

The earliest life on the earth-cyanobacteria

At the beginning of the birth of the earth, there was no oxygen in the atmosphere on the earth, but there was a lot of carbon dioxide. Cyanobacteria inhale carbon dioxide and release oxygen through photosynthesis. They are also the earliest oxygen-producing bacteria.

Cyanobacteria secrete a lot of sticky glue to fix themselves on rocks in shallow water, which is also their main living place (algae organisms and colonies still use this method). When a large number of cyanobacteria gather together, a large number of colloids will be secreted, which will not only attach to cyanobacteria, but also to sediments in the ocean. As time goes on, these sediments will pile up layer by layer to form stromatolites.

Stromatolites are the oldest living fossils.

Although it is the oldest life on the earth, cyanobacteria are not extinct, they are still active on the earth, and even often polluted by nitrogen, phosphorus and other elements, resulting in eutrophication of seawater, which brings harm to fisheries and aquaculture. If you want to see the real stromatolites, you can go to the famous Hamelin Pool in Australia.

-The above contents refer to Millay's children's book A Brief History of Life.