Mudpots are acidic features with a limited water supply. Some microorganisms use hydrogen sulfide, which rises from deep within the earth, as an energy source. They help convert the gas to sulfuric acid, which breaks down rock into clay. Various gases escape through the wet clay mud, causing it to bubble. Mudpot consistency and activity vary with the seasons and precipitation. The sights, sounds, and smells of areas like Artist and Fountain paint pots and Mud Volcano make these curious features some of the most memorable in the park.