Four and a half billion years ago, in the swirling infancy of our solar system, a small body took shape near the boundary where water turns to ice — and in October 2023, a NASA spacecraft returned a fragment of that moment to Earth. Analysis of samples from the asteroid Bennu, conducted at ETH Zurich, reveals that Jupiter's early and rapid formation acted as an invisible hand, guiding the mixing of primordial dust across vast distances and giving rise to a class of asteroids that may carry the original recipe from which terrestrial planets — and perhaps life itself — were eventually made. In B