Coprostanol is a sterol, specifically a saturated derivative of cholesterol, that is primarily formed in the intestines through the bacterial reduction of cholesterol. It is found in feces and is often used as a biomarker for fecal contamination in environmental and water quality studies. Its presence can indicate pollution from sewage or animal waste, making it a useful tool in assessing ecosystem health. Additionally, coprostanol has been studied for its potential effects on human health, although its role is not as well understood as that of other sterols.