5,000 species of worms live on the planet. They are witnesses of healthy soil. In 24 hours, earthworms consume more than half their weight in food. They feed on plant waste, rotten wood, dead leaves, etc. Their droppings constitute a fertilizer rich in nitrogen and potassium, that protects the soil from erosion. Depending on the species, a worm lives between two and eight years. Photo credit: Jacob Levine