It emerges from flashing blocks marked with a '?' when they are bumped from below (a convention carried over from Mario Bros., where bumping platforms was the main form of attack). Upon emerging, it then begins to slide to the right (this was later changed for Super Mario Bros. 3, where, depending on what side of the block was hit, the mushroom would head toward the opposite side.)
If the player touches it, "regular" Mario becomes Super Mario: he doubles in size and is able to take an extra hit. Furthermore, Super Mario can break bricks, whereas regular Mario can't. If Super Mario comes across a Super Mushroom the game will instead give a secondary item, such as a Fire Flower or Super Leaf. These allow him to gain better powers, such as the ability to shoot bouncing fireballs as Fire Mario and the ability to fly and glide as Cape Mario. In Super Mario World, Super Mushrooms would also allow Mario to break Spin Blocks with the spin jump, an important tool for certain levels.
In some Mario games, the Super Mushroom heals Mario and friends, such as in Super Mario RPG: Legend of the Seven Stars, Paper Mario, and Mario & Luigi. It gives the player a short boost of speed in the Mario Kart series. In Super Smash Bros. Melee and Super Smash Bros. Brawl, the Super Mushroom causes the player's character to grow to an immense size.
Shigeru Miyamoto stated in an interview that the Super Mushroom was created by chance. The first sketches of Mario turned out to be too big, for which they were forced to shrink them. Then the development team thought it would be interesting to have Mario grow and shrink by eating a magic mushroom, just like Alice's Adventures in Wonderland. In the novel, Alice eats pieces of mushroom to change her size. This concept is explored further in New Super Mario Bros., with Mini Mushrooms that shrink Mario into an even smaller size than he usually starts out in, and Mega Mushrooms that turn Mario into a colossal giant.
The Super Mushroom slides toward Mario. When it touches him, it disappears, causing him to earn 1,000 points and double in size getting extra abilities. Because the Mushroom is the most basic power-up, without which other powers can't be granted, it is occasionally used in the Mario series to denote basic rewards or easier skill levels. Winning three consecutive Mushroom cards from the slot-machine goal boxes at the end of each level in Super Mario Bros. 3 will earn the player two extra lives, whereas winning three consecutive Fire Flower cards earns three extra lives, and winning three consecutive Starman cards will earn them five. In the Mario Kart games, the first (and easiest) tracks belong to the Mushroom Cup.
- The Super Mushroom makes a cameo appearance in the Nintendo game Metroid Prime Hunters for the Nintendo DS, on the top of a mushroom-like creature.
- The Super Mushroom makes an appearance in Disney film Wreck-It Ralph. Ralph finds a Mushroom in the Tapper scene in the Lost and Found.