Cube

From SmashWiki, the Super Smash Bros. wiki

A Cube is a small box that appears in the Subspace Emissary. There are two varieties of cubes, both of which are opened when attacked to release items. Cubes can be stood on until broken, which may help in rooms where there are falling platforms.

[edit] Turquoise Cubes

Turquoise Cubes are light in color and appear every time you enter an area. They may contain items, collectables, healing items, or Stock Balls. A cube will contain the same variety of items each time, but the specific item(s) inside may vary. For example, a Turquoise Cube may always release shooting items. When it contains healing items, it may have multiple foods (like a Party Ball), two Maxim Tomatoes, or two Heart Containers. The quality of the item(s) depends on the difficulty level, stickers attached to the character, and whether continues have been used while playing.

[edit] Orange Cubes

An Orange Cube appears on a level only until you break it the first time. They only contain collectables, as to increase the Clear %. They typically are tucked away in hidden rooms or alcoves. If there are still Orange Cubes inside of a stage after it has been cleared, a flag will appear on the level in the world map. For an Orange Cube to count, it not only has to be broken, but the contents must be collected.

While the Dojo and other sources like it refer to the color of these as orange, many observers describe their color instead as gold and therefore refer to them as Gold Cubes or Golden Cubes.