Zodletone Mountain is an isolated rise in southwestern Oklahoma whose modest height still makes it a prominent landmark in the flat Anadarko Basin and the northernmost link of the Slick Hills Range. Its broader significance comes from Zodletone Spring on the mountain’s northern slope, a rare sulfide-rich, strictly anaerobic artesian spring associated with a hydrocarbon seep. Since 2001, researchers from the University of Oklahoma and Oklahoma State University have used the spring as a natural laboratory for microbiology and geology. Studies of its unusual chemistry and diverse microbial life have made it an important analogue for early Earth environments and the evolution of complex cells.