Hydrogenobacter acidophilus (high-dro-jen-owe-back-ter ass-sid-off-ill-us) is found at some of the hottest regions, often above 60 degrees C. In nature, it takes the forms of filaments which collect together and are visible with the naked eye as white wispy threads - seen here to either side of the flowing water at the source of Nymph Creek. a thermal site within Yellowstone National Park, Photograph by Kathy Sheehan and David Patterson.