There are four locations on the main circular map that have groups of four stones side by side. In each set, a different stone is the largest stone. When you get the Mask of Truth and talk to the stones, you'll learn that each type of instrument (pipes, drums, guitar) makes the center stone turn a different color.

Choose an instrument, and play that same instrument in front of each large stone. For example, the drums will turn the stones red. As you do each group of stones, another set will turn that color. Once you do all four sets, you'll get a piece of heart.

Location of stones:

• To the north by the stone/grass split, near the town, in a hole
• To the west, by the right hand fountain, under a big boulder
• To the north, to the northern side of the observatory, in a hole
• To the south, on the very bottom of the map against the 'forest wall'