Stem-cells have been called "the holy grail of biology" because they have the capacity to become any of the other cells of the body. Additionally, engineered cells might be used to reseed the body, as one would a tired-old-lawn. These cells might not even be derived of human stock, but could be of anything that could be made histocompatible, producing what might be called a somatic-chimera, a creature altogether new to the world.