Moon Stone

The Moon Stone is a stone shaped like a crescent moon. It appears in the game Paper Mario: The Thousand-Year Door. Along with the Sun Stone, Mario needs the Moon Stone to gain access to Hooktail Castle. Both the Moon Stone and the Sun Stone are found in Shhwonk Fortress and are protected by Fuzzies. Its in-game item description reads, "A mystical stone shaped like the moon."

It is not to be confused with the Lunar Stone from Paper Mario.

Trivia

 * This item shares its name with the Moon Stone from the Pokémon series, which is used to evolve certain Pokémon.