There are two types of millstones: the single-legged millstone and the two-legged millstone. In Korea, the two-legged millstone was particularly common. The millstone was an essential tool in the lives of ancient people, and in some cases, it was also considered a symbol with magical or ritual significance. One such belief was that when epidemics like smallpox or measles spread, women would steal a millstone from another village in the middle of the night and perform a ritual to ward off the disease. Of course, they didn't literally steal it; it was part of an unspoken agreement between villages to help prevent the spread of disease. In many cases, the millstone was willingly given, and after the ritual, it would be returned.