|Kind of Item||Mushroom|
|First Appearance||Mario Maker|
|Latest Appearance||Mario Maker|
|Turns Mario into Costume Mario|
| Mini Mushroom|
The Mystery Mushroom is a power-up that first appears in Super Mario Maker. It resembles the sprite of a Super Mushroom from Super Mario Bros. with a question mark printed on its cap. If Mario touches one, he will transform into Costume Mario and take the form of one of various costumes, most of which are based on non-Mario Nintendo characters. The costumes can be unlocked by completing the 100 Mario Challenge mode; Alternatively, however, if the player scans certain amiibo, an 8-bit sprite of the amiibo's character will appear on-screen, which can then be placed inside a block, turning it into a Mystery Mushroom. Upon touching one while playing, Mario will take the appearance of the 8-bit sprite himself. It has the same effect as an ordinary Super Mushroom as it grants Mario an extra hit point and allowing him to break bricks, except it maintains or shrinks him down to (depending on his current state) Small Mario's size. Mystery Mushrooms can only be used in the Super Mario Bros. style of the game.
Appears in Nintendo 30 in many of the games. It takes on a different function and style in this though: once you tap your amiibo down, all fire flowers will be turned into Mystery Mushrooms with a firing capability.
Reappears in Super Mario Maker Phi, acting identical to Super Mario Maker with some small differences. There are 250 Costumes in Super Mario Maker Phi to begin with, with 10 of them being locked until Princess Fusee is unlocked. All costumes work with all characters.
The Mystery Mushroom resembles the sprite of a Super Mushroom from Super Mario Bros. with a question mark printed on its cap. In the editor, it takes the appearance of the sprite specified.