<span>they have fossils and pieces of the environment from the past inside of them</span>
Answer:
Early cyanobacteria in stromatolites are thought to be responsible for increasing the amount of oxygen in the primeval Earth's atmosphere through their continuing photosynthesis. They were the first known organisms to photosynthesize and produce free oxygen.
Hope this helps!!!
Answer:
can you please show us what the options are and I can for sure help you out?!
