Gamma ray bursts are among the most luminous explosions in the universe, briefly outshining entire galaxies in a violent flash of energy. For decades, scientists have debated what powers these incredibly powerful detonations and, to date, the leading candidates have been black holes or highly magnetised neutron stars called magnetars. Distinguishing between the two has proven frustratingly difficult though but a new study has just provided the clearest evidence yet that magnetars can indeed power some of these extreme events, and they did it by detecting something unexpected, the "heartbeat" of a newborn star.