Mega Mushroom

The Mega Mushroom is a rare variety of mushroom found in the Mushroom Kingdom. When eaten, they grow their consumer to a massive size, allowing them to walk over and destroy everything in their path, including the biggest and meanest enemies. Mega Mushrooms made their debut in Mario Party 4, where they were depicted as normally proportioned mushrooms with green caps, however their current appearance is quite different and unique amongst the Mushrooms of the Mario series. Introduced in New Super Mario Bros., the current Mega Mushrooms have bulbous, orange-yellow caps with red spots, and while all other mushrooms slide along the ground, the Mega Mushrooms hop. Originally, they would actively flee from Mario, and if the player jumped over one, it would even change directions, although this trait was omitted from the Mega Mushroom's New Super Mario Bros. 2 appearance.

Mario Party 4
Mega Mushrooms first appeared in Mario Party 4, with a light green cap (resembling a 1-Up Mushroom). It can be obtained by landing on a Mushroom Space, purchasing it from an item shop, getting it from an Item Bag, or winning a mini-game on the board. They let the player roll two Dice Blocks at once, making the player grow huge and crush other players as they stomp across the board, stealing ten coins from them. However, board events will be bypassed (except for events involving Bowser at Bowser's Gnarly Party). Additionally, a Super Mega Mushroom is available, colored entirely translucent green. The Super Mega Mushroom does the same thing but with three Dice Blocks.

Super Mario 64 DS
While the Mega Mushroom did not make an appearance in Super Mario 64 DS, the Super Mushroom has the same effect as a Mega Mushroom, as it makes the character giant.

New Super Mario Bros.
Mega Mushrooms later reappeared in New Super Mario Bros., where they again made Mario grow to a giant size. In this colossal form, Mario could stomp across the level and crush anything in his path - enemies, blocks, Warp Pipes, and even the Flagpole at the end of the level. When items were crushed by Mario, the bar at the top would start to fill up with yellow. As the yellow line reached the end of a segment, that segment would turn green. After Mario's size reduced again, a 1-Up Mushroom would appear for each green segment filled, with a maximum of five 1-Ups. These mushrooms were rarely found, and almost always came from Toad Houses or Red Flying Blocks. Besides the Toad Houses, they only appear in four levels: 1-1, 1-2, 4-4 and 7-5. The player is not completely invincible in this form, however; if the player was to jump and land on a hole covered with bricks, the player would fall through, thus, losing a life, if the hole is big enough. Additionally, if Mario or Luigi were to do a Ground Pound after eating a Mega Mushroom, a group of Goombas or Coins (or both) would fall from the sky. In other cases, Mario, or Luigi, lose a life if they fall in lava or the purple poison.

In the beta version of New Super Mario Bros., the Mega Mushroom had the same color as the Super Mushroom, but was changed to yellow and red in the final version.

New Super Mario Bros. 2
The Mega Mushroom returns in New Super Mario Bros. 2 after their absence in New Super Mario Bros. Wii. They retain the same function as in the first New Super Mario Bros., but Mario cannot gain 1-Up Mushrooms for the destruction they cause. However, he can get 1-Up Mushrooms by knocking the Flagpole in the big form. This is easily done in World 5-6.

Mario Kart Wii
In Mario Kart Wii, the Mega Mushroom is an item obtained from the Item Box. When players use this item, they become bigger, able to crush other players for a certain amount of time, reducing their speed. While this item is active, the players cannot slow down when going off-road, and they are immune to all items, except for the Star, Bullet Bill, and Thunderbolt. If players get hit by a Thunderbolt while they are big, they shrink back to normal size rather than becoming tiny. The effect also ends prematurely if players fall off the course. The Mega Mushroom's theme music from New Super Mario Bros. is played for the duration of the item's effect.

Mario & Luigi: Bowser's Inside Story
In Mario & Luigi: Bowser's Inside Story, Broque Monsieur sometimes attacks by using a Mega Mushroom to make himself giant. Bowser needs to punch his body to avoid the attack. Then Broque Monseiur's head will fall off, still giant, and Bowser needs to punch his head.

Mario & Sonic at the Olympic Winter Games
In Mario & Sonic at the Olympic Winter Games, the Mega Mushroom appears in the Dream Event, Curling Bowling, and Balloon Blast. The actual item does not appear, but there is an Item Box that it could be obtained from. The Mega Mushroom makes the character 2x his or her original size.

Trivia

 * In Super Paper Mario, there is an equivalent item to the Mega Mushroom, called the Mega Star, which has almost the same effects as New Super Mario Bros..
 * Fire Yellow Toad's cap in New Super Mario Bros. Wii has a coloration very similar to the Mega Mushroom as it turns yellow and his spots become red.
 * In New Super Mario Bros. and New Super Mario Bros. 2, if Mario uses a Mega Mushroom and reverts back to regular size, he will be Super Mario regardless of what form he was before. However, if he uses it and the space is too small for him to grow, he will keep the power-up he had prior to enlarging.
 * If Mario or Luigi ground pounds a block containing a Mega Mushroom, it still pops out from above.
 * The Mega Mushroom is planned to make a cameo appearance in the Wii U version of Tekken Tag Tournament 2 as part of its exclusive content.