Desulfurococcus mucosus is a hyperthermophilic archaeon in the family Desulfurococcaceae, thriving in hot, anaerobic environments such as hot springs and hydrothermal vents at temperatures above 80°C. It is an obligate anaerobe that reduces sulfur as an electron acceptor during metabolism. Its cell surface is covered in a characteristic mucous-like S-layer that gives it its species name.