Underground ecosystems refer to the complex networks of life that exist beneath the Earth's surface. These ecosystems include various organisms such as bacteria, fungi, earthworms, and insects that play crucial roles in nutrient cycling and soil formation. They thrive in dark, moist environments, where they contribute to the health of the soil and support plant life above ground. The interactions within underground ecosystems are vital for maintaining ecological balance. For instance, mycorrhizal fungi form symbiotic relationships with plant roots, enhancing nutrient absorption. Additionally, earthworms aerate the soil, improving its structure and water retention. Together, these organisms create a thriving habitat that supports life on the surface.