World Star (New Super Mario Bros. 2)

World Star is the final world that appears in New Super Mario Bros. 2. It has 9 levels and a toad house. Of the levels, there is 7 numbered levels, a castle and a rainbow level. It requires 90 Star Coins to enter it. An additional 9 Star Coins are needed to access the only Toad House in this world. Dry Bowser is the boss of the castle. It can be unlocked by beating Bowser in World 6. Unlike the first eight worlds, has Moon Coins, instead of Star Coins. World Star appears to be similar to World 9 and World S, as they are all bonus worlds unlocked by beating the final boss.

Trivia

 * This is the only special world to not be unlocked via a cannon.