A worm is a long, creeping animal, with a soft, often segmented body. They don't have legs but instead are covered in hairs or bristles that help them to move. They breathe through their skin, which must remain moist to absorb oxygen from the air.
They've existed for about 600 million years. There are about 34,000 different types of worm; many are so small you wouldn't be able to see them without a microscope!
Worms are hermaphrodite, which means they don't need another worm to reproduce. They lay their eggs, which hatch as little worms. Worms can live for up to 10 years.
Worms eat their own weight in organic waste, soil and minerals and excrete their own weight in castings daily, which makes compost and enriches the soil. One acre of worms can break up about 50 tonnes of soil. They don't eat living plant tissue, and so don't hurt plants either. They truly are a gardener's best friend! Some people even keep them as pets, feeding them on kitchen scraps just so the worms can make them lots of lovely compost for their gardens.