As soluble iron started to get used up, O2 began to build up in atmosphere, CO2 dropped. Earth went into oscillating glacial ages - even at equator. Experiments show that even algal scum on crushed rock enhances weathering by several times to several orders of magnitude. But at about 1.9 billion years we start to see fossils of much larger cells. These cells belong to the Eukaryotes - of which we are members.
Eukaryotic cells are symbiotic colonies of prokaryotes many of the symbionts called organelles.
O2 handled by Mitochondria, chloroplasts handle photosynthesis. These organelles independently replicate with their own genome DNA sequences in a circular strands, as in bacteria. Several other kinds of organelles are similar. Red beds are very shallow-water, river, or soil deposits in which the iron has combined with O2 for form red iron oxide. These are called the Ediacara assemblages.