? Coin

A Question Coin is a special Coin in Super Mario Galaxy and Super Mario Galaxy 2. Question Coins appear in many galaxies all over both games. When one is obtained one of the following things will appear:
 * A line of musical notes.
 * An accumulation of Star Bits or Coins.
 * A power-up.
 * Another question coin.

Most of the time Mario has a time limit to collect whatever appears and if he completes the collection within the time limit, he will receive a prize. Most commonly it is one 1-up but it is also possible for it to be 3 1-ups, a power up, more coins or star bits or, very rarely, a Rainbow Star.