In 2016, geologists discovered an extraordinary phenomenon deep beneath a Canadian mine—a water source trapped in rock for over 2.6 billion years. This discovery sheds new light on microbial life forms, both ancient and potentially existing elsewhere in the universe. The Discovery of the Oldest Water on EarthWhen the geologists, led by Professor Barbara Sherwood Lollar, first stumbled upon the ancient water, they were unprepared for the scale of what they would find. “The sulfate in this ancient water is not modern sulfate from surface water flowing down. When she tried it, she discovered that the ancient water was “very salty and bitter” and far “saltier than seawater”—exactly what she had hoped for.