A stygobiont is an organism that lives in groundwater, particularly in subterranean environments like caves and aquifers. These creatures are adapted to life in complete darkness and often have unique physical traits, such as reduced eyesight or lack of pigmentation. Stygobionts play a crucial role in the ecosystem by contributing to nutrient cycling and maintaining water quality. Common examples of stygobionts include certain species of crustaceans, insects, and fish. These organisms are often studied in the field of biospeleology, which focuses on life in caves and other underground habitats. Understanding stygobionts helps scientists assess the health of groundwater ecosystems and the impacts of environmental changes.