Using the Very Large Telescope and the radio telescope ALMA in Chile, a team of astronomers including researchers from the Niels Bohr Institute has discovered a swarm of galaxies orbiting the surroundings of a hyper-luminous and vigorously star-forming galaxy in the early universe. The observation provides important clues to how exceptionally bright galaxies grow, and to how they evolve into energetic quasars, beaming light across most of the observable universe.