Ancient microorganisms found in halite may have implications for search for life

Primary fluid inclusions in bedded halite from the 830-million-year-old Browne Formation of central Australia contain organic solids and liquids, as documented with transmitted light and UV-vis petrography. These objects are consistent in size, shape, and fluorescent response to cells of prokaryotes and algae, and aggregates of organic compounds. This discovery shows that microorganisms from saline depositional environments can remain well preserved in halite over hundreds of millions of years and can be detected in situ with optical methods alone. This study, published in Geology, has implications for the search for life in both terrestrial and extraterrestrial chemical sedimentary rocks.