Collins Big Cat, 2015 • 80pp

Don’t look now, but you’re surrounded. You’re sharing a room with billions of living things. They’re under your feet, and on every surface. They’re all over your skin, and even inside your body. But you’ll never spot them. We can only see these tiny organisms with the help of a microscope.

Like all living things, microorganisms spend their time moving, feeding, growing and making copies of themselves. When they do these things inside plants and animals, some microorganisms cause harm. But more often, microorganisms help plants and animals, including humans. In fact, we couldn’t survive without them.