Lumbricus terrestris, commonly known as the common earthworm, is a species of earthworm found in soil across Europe and North America. These worms play a crucial role in soil health by aerating the ground and breaking down organic matter, which enriches the soil with nutrients. They can grow up to 30 centimeters in length and have a segmented body that helps them move through the soil. Earthworms, including Lumbricus terrestris, are hermaphrodites, meaning each individual has both male and female reproductive organs. They reproduce by exchanging sperm with another worm, leading to the formation of cocoons that contain fertilized eggs. Their presence in the soil is vital for maintaining ecosystem balance and promoting plant growth.