Trovants, also known as "the growing stones", are a type of spherical-shaped sandstone concretions that can be found in the Vâlcea County of Romania, particularly in the villages of Costești and Bănița. These geological formations are unique in that they are believed to have the ability to grow, and can sometimes reach sizes of several meters. The process by which they grow is not well understood, but it is thought to be related to the mineral content of the surrounding soil and the presence of certain chemicals in the groundwater. Trovants are considered a rare geological phenomenon and are a popular tourist attraction in the region.