Geobiology

Imagine a place deep in the ocean where special rocks constantly react with water, releasing energy-rich gases like a natural, non-stop battery. This process also makes the water extremely alkaline, like a weak bleach. Scientists found tiny microbes living in the mud there, surviving by 'eating' these gases. They acted like detectives, analyzing the fatty molecules (lipids) left behind by these microbes in the mud. These 'molecular fossils' told them not only that life was there, but also what it was eating. They discovered that the microbes' diet changed over time, switching between making methane and eating methane, depending on what other 'food' was available. They also saw that these microbes build special, tough cell walls to protect themselves from the harsh, alkaline conditions.