Do you think earthworms are cool creatures that are fun to play with? Or are they icky, creepy, slimy crawlies that you'd rather avoid?

If you're a fisherman, you probably like them since they can help you reel in the big fish when used as bait. But what if you're a gardener?

Anyone who spends time in a garden will tell you earthworms are a gardener's best friends. In fact, earthworms may be the most important factor in the success of a garden. Some people even call earthworms "nature's first gardeners"!

If you've ever been around a farm in spring, you know that farmers need to plow the soil. Plowing breaks up the soil, allowing air and water to get to seeds and the roots of plants. Earthworms act like tiny plows when they live in a garden.

As earthworms move through the soil of a garden, they make tunnels. Just like plowing, these tunnels allow air and water to get to the roots of plants.

Without access to air and water, plants would not grow well, which is why you might notice that plants sometimes don't survive if the soil they're in is too dry and compacted.

Just about all soil has earthworms. The better the soil, the more earthworms you'll find. There are four common types of earthworms you're likely to run into: night crawlers, garden worms, manure worms and red worms.

As earthworms live their lives in the soil, they eat organic matter, such as dead leaves, grass clippings and even dirt. After they digest their unique meal, earthworms produce excrement that helps enrich the soil further.

Their waste — called "castings" when found on top of soil — helps gardens grow because it's rich in phosphorus, calcium, nitrogen and magnesium. These are all important nutrients that help garden plants grow and stay healthy.

Gardeners who want to increase the number of earthworms in their garden soil can do so by adding more organic matter to their garden. Mulched leaves or grass clippings will draw more earthworms to their soil, and, in turn, the earthworms will enrich the soil with their tunnels and castings.

Scientist Charles Darwin once had this to say about the role of the lowly earthworm:

"The plow is one of the most ancient and most valuable of man's inventions; but long before he existed, the land was in fact regularly plowed and still continues to be thus plowed by earthworms. It may be doubted 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."

Wonder What's Next?

Tomorrow’s Wonder of the Day is all about horsepower, but there won’t be any manes or hooves in sight! Vroom! Vroom!