The Sun Stone Medallion and Moonlight Stone Medallion are key items from Alex Kidd in Miracle World. They are a pair of medallions necessary to open the sealed door at Cragg Lake, where the Gold Crown is hidden.
The player already begins the game with the Sun Stone Medallion in Alex Kidd's possession, while the Moonlight Stone Medallion is obtained upon defeating Janken the Great.
If the player does not physically acquire the Moonlight Stone Medallion following the final Janken battle then it will still be in the player's inventory on the final level.