Árbol de Piedra ("stone tree") is an isolated rock formation in the Eduardo Avaroa Andean Fauna National Reserve of Sur Lípez Province, Bolivia.[1] Much photographed, it projects out of the altiplano sand dunes of Siloli in the Potosí Department, about north of Laguna Colorada. Known as the "Stone Tree," it is shaped like a stunted tree about 7 m high. Its shape, particularly the thin stem, is due to strong winds carrying sand and eroding the soft sandstone.[2] [3]