Immortal blood is a term given to blood that lives outside the human body much longer than it is supposed to. A normal person’s blood usually lives outside the body for two and a half to four days. Immortal blood can live outside the human body in excess of twenty-seven days. Depending on the conditions and where the blood is kept. In Bob Beck‘s case the blood was kept in microscope slides unsealed. If the slides were sealed the blood samples would last much longer.