Astronomers know that in the early Universe, black holes with masses many times that of the Sun roamed space. But they’re not sure where these monsters came from. Enter a new theory – black hole stars. Black hole stars were supermassive stars in the early Universe. At their centres were massive black holes, formed by crushing gravity. As a supermassive star became more massive and grew, the black hole at its centre would have gorged on the star’s gas and would also have grown. Eventually the star would begin to die as it cooled down and, in doing so, would expose the massive black hole at its heart.