The variety of hydrothermal (hot water) features in Yellowstone is endless. Actually, Yellowstone contains half of the hydrothermal features in the whole world! They come in many types, but one of the most intriguing is the mudpot.
Mudpots are created when hydrogen sulfide gas, microorganisms, and heat combine to create a wet, acidic environment that breaks down the surrounding rock into a bubbling clay. They are often called “paint pots” because depending on the rock they are made of, they can come in a wide variety of colors.
Check out the Yellowstone National Park Service website for more in depth information about mudpots.