The earthworm is a long, segmented invertebrate that lives in soil. It plays a crucial role in the ecosystem by aerating the soil and breaking down organic matter, which helps improve soil fertility. Earthworms are typically reddish-brown and can grow up to several inches long, depending on the species. Earthworms are hermaphrodites, meaning each individual has both male and female reproductive organs. They reproduce by exchanging sperm with another earthworm. Their movement through the soil creates tunnels, allowing air and water to reach plant roots, which is essential for healthy plant growth and overall soil health.