>>1036361
Indeed. Oxygen is the waste of plant life, its like shit in our case. It isn't just flammable, but it was essentially a poison dangerous to life unless CO2 which is one of the life necessities for plants. And back in the day when plants started to shit the atmosphere full of oxygen it was a danger to life itself.
Quite a few couple of years had to pass until lifeforms developed that could use the oxygen to support their life.