Zombie skin cells, that is. This sci-fi sounding term is used to describe senescent skin cells that have outlived their usefulness, but don’t ever really die. Now, we may know why zombie skin cells have this double agent-esque existence. “We’ve known that senescent skin cells are different from senescent immune cells or senescent muscle cells. Three of these are distinct to senescent skin cells and the researchers labeled them C7, C10, and C11.