Super Acorn

The Super Acorn is a power-up item that debuted in New Super Mario Bros. U. The item resembles an acorn with red and yellow stripes on top and a red face with eyes on the bottom. It transforms playable characters into their Flying Squirrel forms. There exists a stronger variant called the P-Acorn.

New Super Mario Bros. U / New Super Luigi U / New Super Mario Bros. U Deluxe
In New Super Mario Bros. U, New Super Luigi U and New Super Mario Bros. U Deluxe, Super Acorns appear as common items introduced in each game's first level. They originate from a large Acorn Tree in Acorn Plains, as seen in the games' introduction; during gameplay, they are usually found within ? Blocks, but also carried by Waddlewings, which the player has to defeat in order to release the Super Acorn. Upon release, Super Acorns start rolling on the ground and change direction when they touch a wall, similarly to how a Super Mushroom acts. When collected, they confer Flying Squirrel abilities, such as gliding and sticking to walls for a short time.

There are some Super Acorns rolling around in some parts of the world map, where they can be collected instantly and stored into the inventory.

Super Mario Maker 2
Super Acorns were added to Super Mario Maker 2 in the version 3.0.0 update released on April 22, 2020, appearing in the New Super Mario Bros. U style. In the nighttime ground theme, Super Acorns bounce at varying heights as they travel across the ground.

Other appearances and cameos
In Super Mario Maker's E3 2014 trailer, Super Acorns can be seen in the Acorn Tree in the background at the beginning of a New Super Mario Bros. U-style ground course. The Acorn Tree along with its Super Acorns were removed prior to the game's release.

In the Super Mario Mash-Up Pack for Minecraft, Cocoa Beans are replaced by Super Acorns.

New Super Mario Bros. U Deluxe

 * North American website bio: "This power-up will make you look like a flying squirrel-and glide like one, too!"
 * European website bio: "This nifty nut transforms your heroes into Flying Squirrels, granting them the gift of graceful gliding! They can even grab onto walls for a brief time, making this one potent power-up!"

Play Nintendo

 * New Super Mario Bros. U Deluxe Power-Ups Trivia Quiz: "The Super Acorn power-up will make you look like a flying squirrel—and glide like one, too."