cyanobacteria
4 billion years ago the earth was lifeless, it was a hot carbon-rich environment. It contained no oxygen. But somehow, tiny microbes started to evolve. One of them was called cyanobacteria. Cyanobacteria adapted very well to the carbon-rich environment. It poisoned its enemies. They photosynthesized which led to the production of oxygen. But oxygen was toxic to life living in carbon-rich environments. So pretty much all microbes perished including a large number of cyanobacteria. But the surviving cyanobacteria not only adapted to oxygen-rich environments but also learned how to use it through a process called AKA breathing. Cyanobacteria started to breed like crazy again. But as the oceans got cooler, algae started to and algae stole nutrients from cyanobacteria, and they outcompeted cyanobacteria. The algae send the cyanobacteria to the dark parts of the ocean and then more complex life evolved like humans. But the success of humans has led to the success of cyanobacteria. We have released carbon dioxide which cyanobacteria love and we overdo our farms with fertilizers that fertilizer gets into the ocean and helps cyanobacteria grow even more while keeping algae at bay. This is bad because cyanobacteria release toxic stuff into the ocean which kills marine life, the same thing happens with all the water bodies. They disrupt the entire ecosystem. Due to cyanobacteria, entire species could go extinct. Also, cyanobacteria live very short lives and die in masses which pollutes the water even more. We must stop releasing greenhouse gas and putting too much fertilizer on our farms. If we do all this, we can save entire species including ours from going extinct.
