It is the symbol of the city of Covasna, a muddy volcano, a permanent eruption of gases - carbon and sulphur oxides - that keeps a vortex of yellow mud and groundwater or minerals moving. The carbon dioxide emissions here are closely related to the volcanic processes that took place in the region between Harghita and Calima somewhere towards the end of the Paleocene. The gases emitted consist of carbon dioxide with a maximum purity of 98%. These gases can be found in almost the entire area of the city of Covasna, they collect in specially designated rooms, the so-called skunks, and represent a unique natural factor that is of very special importance in the treatment of numerous diseases of the cardiovascular system.
According to the descriptions, this natural phenomenon was located further north in the 17th century, but mysteriously moved to the city center, leaving a younger brother in its old place, the "Little Devil's Puddle". During the 19th century, several eruptions occurred: 1837, 1857, 1864 and 1885, the largest in 1837, the last major gas eruption in 1984. Currently it is completely harmless and resembles a bubbling fountain covered by a metal grid, which can be visited in this form in the center of the city.
Note: Skunks are mofettes