Pobiti Kamani is a rock phenomenon located in Varna Region, on the road between Varna and Sofia around several villages just west of Varna. It consists of several groups of natural rock formations on a total area of 70 km². The formations are mainly stone columns between 5 and 7 meters high and from 0.3 to 3 meters thick. The columns do not have solid foundations, but are instead hollow and filled with sand, and look like they are stuck into the surrounding sands, which gives the phenomenon its name. There are a number of theories regarding the phenomenon's origin, divided roughly into two groups — supporting an organic or a mineral origin.