Getting blood from a stone is impossible, but growing blood from 3D mini hearts is now a reality. A research team led by Robert Zweigerdt, a developmental biologist at the Hannover Medical School, previously used human pluripotent stem cells to produce heart-forming organoids (HFOs) in a dish.1 These mini primordial heart constructs display the multiple tissue layers that exist in the developing human heart. They also contain the latent capacity to produce blood cells.