The term Trovant is specific to the Romanian geological literature and was introduced first by the naturalist Gh. M. Murgoci in this work "The Tertiary in Oltenia".
The trovants, also known as "growing stones", are geological formations found in sand accumulations and sandstone deposits cemented by waters rich in calcium carbonate. They appear as mineral units, nodular, spherical or cylindrical with massive, concentric or plain structure ranging from a few millimeters to several meters. The trovants have a hard stone core, but their shells are made of sand. They trovants represent a cementation in the reservoir of sand that contains them in various shapes, some of the very strange. 6 million years ago there was a sedimentation basin here. The sand reservoir was formed as a consequence of the successive sedimentation of detritic material, transported by rivers from the continent. Along with this sediments, from the water get accumulated chemical substances in excess (carbonates). The, over the first beds of sand the sedimentation continues and the sand get compressed under the beds above. the water is eliminated through the empty spaces between the sand particles, that get pressed. Trovants grow spontaneously from the center to the margins - with a deposition rate of about 4-5 cm in 1000 years.
Trovants can be found in Romania at two locations in Vâlcea County. The first location is a sand quarry on the left side of DN67, before the entry in Costeşti village. On an area of 1100 m2 there are several trovants of various forms, several tons heavy, extracted from the steep sand quarry wall. The second location, and the most spectacular, is along Gresarea Brook that flows into a river in the nearby of the Oteşani village, approximately 15 km from Horezu. Going up the Gresarea brook you will find trovants in many forms, with weights ranging from only a few grams to hundreds of kilograms. Trovants can be seen at the "Trovants Museum" Natural Reserve in Costeşti, Vâlcea County, declared UNESCO monument,
The stone formations with alien features lie dormant, witnesses to the passing of time; that is – until it rains. Not long after the last drops of water fall, they begin a multiplication process. Small oval or round blain-like forms appear on the upper part of them. Many people are amazed and even locals are impressed when after heavy rainfall these rock formations begin to ‘live’. Locals have aptly dubbed them, “growing stones”.