The secret world beneath our feet is mind-blowing – and the key to our planet’s future

Don't dismiss soil: its unknowable wonders could ensure the survival of our species

Beneath our feet is an ecosystem so astonishing that it tests the limits of our imagination. It's as diverse as a rainforest or a coral reef. We depend on it for 99% of our food, yet we scarcely know it. Soil.

Under one square metre of undisturbed ground in the Earth's mid-latitudes (which include the UK) there might live several hundred thousand small animals. Roughly 90% of the species to which they belong have yet to be named. One gram of this soil - less than a teaspoonful - contains around a kilometre of fungal filaments.