From the Super Mario Wiki
The Super Mini Mushroom is a Mushroom that only appears in Mario Party 4. It is a translucent, glowing Mini Mushroom.
The Super Mini Mushroom is an item that turns its user into a pint-sized version of themselves, similar to the normal Mini Mushroom. However, a player using it only is able to move five or less spaces. The Super Mini Mushroom, although more expensive and rare, overcomes this problem by allowing the player to strike two Dice Blocks numbered one through five. If a player is lucky enough, it is possible to move the normal maximum amount of ten spaces through this method. The effects of the Super Mini Mushroom wear off when the player moves the number of spaces decided by the dice block.
Super Mini Mushrooms can be won during the minigames on the board, the Lottery Shop, or through the Item Shops. Unlike normal Mini Mushrooms, they cannot be found on a Mushroom Space.
While mini, players can play special pint-sized minigames if they pass certain locations on the board. Depending on the game, the player has a chance to win an item or some coins. Additionally, a player can pass through small orange Gates, too small for normal sized players. The reactions to players by characters on the board or the effect of a board event on the player may also change.
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