Moon Rock

Moon Rocks (initially called Mysterious Cubes in the Prima Games guide ) are lustrous, gray cubic objects found in Super Mario Odyssey. There is one in each kingdom visited (excluding the Mushroom Kingdom, Dark Side, and Darker Side), but they have no function until after Bowser is defeated in the Moon Kingdom. After defeating Bowser and collecting all of the Multi Moons in a given kingdom (if there are any), that kingdom's Moon Rock will glow, and Mario can activate it either by throwing Cappy at it or Ground Pounding on it. Upon activating a Moon Rock, it will fly into the sky and explode, causing more Power Moons to become available in that kingdom. Toadette also gives Mario a Power Moon for activating all of the Moon Rocks.

Similarly textured rocks can be found in the Moon Kingdom, most prominently during the escape sequence at the end of the game. Interestingly, the same texture is also found on the colored material that makes up many of the "another world" secret areas.

Trivia

 * The Wooded Kingdom releases the most Power Moons from its Moon Rock when activated, releasing 22 Moons, while the Ruined Kingdom releases the least Power Moons, releasing 5 Moons.
 * In New Donk City, a few citizens are working on computers. Looking closely at the computers reveals an open page with a picture of the Sand Kingdom's Moon Rock, before it is active.