The oldest evidence of life on Earth has been found.

Rock formations in Western Australia in the Dresser Formation, 3.5 billion years old, have been found to be the oldest evidence of life on Earth. These rocks are stromatolites. Usually they consist of layered rocks, which can be formed either as a result of the vital activity of microbial colonies, or as a result of chemical reactions between the rock and the environment. They can help scientists understand when and where life first arose on Earth, but determining the exact origin of stromatolites is difficult.