Definetly one the birthmark with the most hideous name the Mongolian Blue is mostly harmless and the most chill of all the birthmarks. It is usually bluish and bruise-looking. It appears over the lower back or bum, sometimes in other areas including the body or arms. A birth mark for the darker people of the human race it appears at birth or a bit later and may persist for months or even years (it is almost never seen in later years of life) and does not become cancer or develop other symptoms. Sometimes misdiagnosed as a bruise and a sign of child abuse.

According to any number of medical web sites, the Mongolian Blue Spot is commonly found on infants of "darker skinned races such as Asian, East Indian, and African." It is also found on Native American Indians and even some Eastern European Jews. The blue spot is thought to be evidence of Mongol genetic ancestry.

In traditional Korean culture, the blue spot is said to originate from the grandmother spirit or "Samshin Halmoni" slapping the baby's butt when it is born.