Massive galaxies like our Milky Way and Andromeda typically consist of hundreds of billions of stars and host a single, central black hole with a mass of several million up to several 100 million solar masses at their centers. In 2019, an international research team led by scientists from Göttingen and Potsdam proved for the first time that the irregular galaxy NGC 6240, the Starfish Galaxy, contains three supermassive black holes, the remnant of mergers between three smaller galaxies.