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.