10 April

More than 20 billion tonnes of microbes live beneath the Earth's surface. All life is microbes, who combine in various ways to create other living things we recognise. Also, microbes are immortal, they don't age or die, unless they run out of food and water. Many found underground have dramatically scaled back the speed of their metabolism, to be able to survive tens of millions of years without adequate food and water. If you're tempted to see them as simple life forms, remember they built you. They are you.