 So they are literally, and of course for people who don't know, stem cells are just like the proto-cell. Before a cell becomes anything, it's a stem cell. So a stem cell, they all start as stem cells and then if your body needs skin, it becomes a skin cell. Which is why they can take stem cells and grow... They can grow little tiny brains and hook them up to chips. Or grow ears on rats, you know, that sort of thing.