Most of the planet’s ecosystems are made of a multitude of different species, rich tangles of living things all interacting, competing and cooperating in order to eke out an existence. But not always – in South Africa, within the darkness of a gold mine, there is an ecosystem that consists of a single species, a type of bacteria that is the only thing alive in the hot, oxygen-less depths. It is an ecosystem of one, living in complete isolation from the Sun’s energy.

This incredible and unique habitat was discovered by Dylan Chivian from the Lawrence Berkeley National Laboratory, leading a large team of scientists from 15 institutes. The group was interested in studying extremophiles, species of bacteria that