This is an exceptional example the Earth's oldest fossil, stromatolite, from an unusual South American Precambrian formation. This slab of stromatolite was cut and polished perpendicular to the individual colonial layers and thus exhibits multiple colored growth rings. The stromatolite has been polished to a mirror finish on one side, vividly rendering the inherent beauty of stromatolite and making apparent the biogenic process in its formation. The age is estimated to be 2.2 to 2.4 BILLION years old, near the Lower Paleoproterozoic, from a time in the Precambrian when stromatolite is believed to have been both ubiquitous and abundant on earth. This remarkable specimen is appropriate for display, teaching or research, representing primitive prokaryotic life responsible for forming the atmosphere that we breathe today.