To have the current elements in the Universe, cosmologists believe there had to be several generations of stars, building up heavier and heavier elements. But what did that first generation of stars look like? They were probably huge, weighing 50-500 times the mass of the Sun. They lived quickly and then died as massive supernovae that seeded the surrounding space with heavier elements forged during this explosion. They could even be the source of gamma ray bursts, which are the most powerful known explosions in the Universe.