Earthworm

The lowly worm? Maybe not... Gardeners and farmers love earthworms, since as they burrow through the earth they mix organic matter like rotting leaves and twigs from the surface down into deeper layers. At the same time the worms' tunnels aerate the soil by mixing in oxygen from the air. These are the same things farmers do when they plow or till a field before planting, because plants grow better in soil with more organic materials and oxygen in it— it's more fertile. Because they're so good at making lots of rich, fertile soil, worms are an important part of the ecosystem of healthy gardens and fields.

When Charles Darwin returned to England after his famous trip around the world on the HMS Beagle, he set up a garden of his own and quickly became fascinated with earthworms. The last book he published, in 1881, was about earthworms and how they help to fertilize soil. By then he had a pretty high opinion of them: "I doubt whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures," he wrote. The early Santal people of Northern India would probably have agreed with him. In their creation stories the earthworm was one of the first seven creatures in the world, and it made the land by eating the ocean's bottom and pooing it onto the back of a giant tortoise. Seems plausible...