The oldest known fossils are the stromatolites, found in Western Australia. These structures are composed of layers of sediment that have been built up by colonies of cyanobacteria. However, the nature of the fossilization process that formed these structures was not entirely clear.
Researchers, led by Dr. Kazuhito Naruke from the University of Tokyo, used a combination of experiments and computer simulations to investigate how bacteria can be fossilized in hot springs. They found that the silica content in hot springs is high enough to preserve the silica cell walls of bacteria, even at high temperatures.
In addition, the team found that the hot springs must have had a high rate of water flow to prevent the silica from crystallizing and forming minerals other than opal, which is the mineral that makes up the fossils.
The research suggests that hot springs on the ocean floor were likely the environment in which the oldest fossils, microfossils of bacteria, formed around 3.5 billion years ago.
