The ? Coin or Question Coin, is a special coin in Super Mario Galaxy. It is a large, yellow Coin with a question mark on it. When one has been collected four things can happen. * A Mario theme will play and a line of musical notes will appear for Mario to collect. This usually causes three 1up Mushrooms to appear, or very rarely, a Power Star. * An accumulation of Star Bits or Coins to appear. * A Power Up will appear. * Another ? coin will appear. These coins appear in many galaxies like Good Egg Galaxy.