Keyhole

Keyholes are secret level passages in the game Super Mario World. Every level represented by a red dot on the map signifies the level has a secret exit, and in most levels the exit is through a Keyhole. To reach the secret levels, the player must find a Key (usually hidden in the main course somewhere) and bring it to the Keyhole. If Mario or Luigi is riding Yoshi, Yoshi can hold the Key in his mouth and simply walk to the Keyhole. When activated by the Key, the Keyhole grows in size and swallows up Mario or Luigi, along with Yoshi, if the player is riding him.

Trivia

 * A Keyhole is featured in the Super Mario World animated television series, during part of the "Mama Luigi" episode where Baby Yoshi spat out the Key he held in his mouth at the Keyhole, which allowed Mario, Luigi and Baby Yoshi to rescue Princess Toadstool and return to Dome City.