Adobe

Adobe is a building material made from soil and often organic matter. Adobe means mudbrick in Spanish. It can also mean any kind of earth construction. 
Adobe is one of the earliest building materials ever used. It is found all over the world. The techniques used in adobe construction have not changed since the 16th century in the Southwestern United States. Because they are not fired in a kiln they never become hard. They shrink and swell as the water content in them changes. Also, as they get wetter, they become weaker.
Adobe does not permanently stick to wood, metal or stone because it moves more than they do. This causes cracks and seperation from other materials. Stone is sometimes used as a foundation and wood for the roof. These are usually held in place by their own weight or the weight of the adobe pressing down on them. But adobe construction is cheap and the materials are usually easy to find.