Cubes are transparent containers from The Subspace Emissary. Cubes have two variants, both of which release items if a character attacks it. In some levels, cubes appear in midair, and the player can stand on them until they break it. The floating cubes may assist the characters in rooms with falling platforms.
Turquoise cubes appear every time the player enters a stage. They may contain items, collectibles, healing items, or Stock Balls. Every standalone cube always contains the same type of item, but the specific item(s) inside may vary. For example, a given turquoise cube may always release shooting items, but different ones each time. When a turquoise cube is set to contain healing items, it may have multiple varieties of food (including a Party Ball), two Maxim Tomatoes, or two Heart Containers. The quality of the contained items change based on the difficulty level, a character's stickers, and whether the player used continues or not.
Orange cubes only appear in a stage before the player fully completes it. These cubes only contain collectible items like Trophies, and are most often located in hidden rooms and alcoves.
The player has to collect every item from the Orange cubes to increase the Clear %. Stages where the player has not collected every item are marked with a flag. A stage's flag changes to a flashing crown if the player meets every requirement for that stage, including collecting every item from the Orange cubes.