Archean Eon Coloring Pages Bundle (5 different pages): StromatolitesArchaeaArchean Eon AtmosphereCyanobacteriaGreenstone BeltsThe Archean Eon is the second eon—the time when simple, single-celled organisms— archaea—first appeared. Cyanobacteria produced oxygen through photosynthesis. The Archean atmosphere lacked free oxygen, but over time, oxygen levels began to increase. Explore Archean Rocks- Greenstone Belts, and stromatolites. File Formats:PDF formatEPS vector format for flexibility. Vector