Credit: Courtesy of John Valley, UW–Madison
This sample of rock was taken from the Apex Chert, a rock formation in western Australia that is among the oldest and best-preserved rock deposits in the world, in 1982 and was soon found to contain evidence of early life on Earth. A study published by UCLA and UW–Madison scientists in 2017 used sophisticated chemical analysis to confirm the microscopic structures found in the rock are indeed biological, rendering them — at 3.5 billion years — the oldest fossils yet found. This is the rock after analysis in the WiscSIMS Laboratory.