Sound Stone

From Mother - Wiki on Neoseeker

The Sound Stone is the item used for recording the melodies in the Your Sanctuary locations. This is also used for teaching Paula the music, so she can pray (sing), and defeat Giygas at the end of the game.

How to Obtain

This is obtained at the beginning of the game, when Buzz Buzz gives it to you after he has been stepped on. It is not very wise to throw this away, as it is the only way for you to get into Magicant.

Appearances

This item only appears in Earthbound. It is also believed that the Sound Stone is a small item that appears in the Golden Chamber in Mother 3.