I read somewhere that they are nerve endings in the skin that broke. The ones that sit on the skin are probably some kind of accumulation already in the nerve like blood or something that was there before it broke. I heard you should be careful with a mole that comes off and bleeds b/c they don't stop bleeding. It is suggested that moles be lanced off by a surgeon. I know, I don't like seeing doctors either, and I don't, but I do think they have uses in certain instances such as this.