This is a guide for the Oracle of Ages Heart Pieces. Listed below is the location, and how to earn each Heart Piece. There are 12 Pieces all together across Labrynna.
Oracle of Ages Heart Pieces Guide
Heart Piece #1
In the past, after you get the Shovel, head one screen south of the Black Tower. Here there will be a Heart Piece blocked by dirt mounds. Just use your shovel to gain access to this Heart Piece.
Heart Piece #2
In the past, after your visit with the Maku Sprout, head over to Maku Road and go one screen west. Here, just defeat the enemy, then push the lower-left block up, and the lower-right block left to gain access to the Heart Piece
Heart Piece #3
In the present, after you have earned the Power Bracelet, go to southwestern section of the Yoll Graveyard. Just use the Power Bracelet to life the large stone in front of the Heart Piece.
Heart Piece #4
In the past, go two screens west and one south of the Wing Dungeon in the Deku Forest. Here burn the sapling with an Ember Seed to reveal a cave. Once in the cave, you can claim your prize.
Heart Piece #5
In the past, head west from Lynna Village until you can go no further. From here, head north and enter the cave. Inside, use Roc's Feather to jump the gaps and use the Power Bracelets to move the pots so that you can grab this Heart Piece.
Heart Piece #6
In the past, start at the house that had the Tuni Nut in Symmetry Village. From here go west, south, west, north, west, and stand in the southwestern corner of the screen. Play the Tune of Currents to enter the present. Now just head east to claim the Heart Piece.
Heart Piece #7
In the past, head to Lynna Village and go one screen north of the Ember Tree. Stand directly, above the two trees in the center of the screen. Now use the Tune of Currents to enter the present. Welcome to the Secret Shop. Here you can purchase the Heart Piece for 500 rupees.
Heart Piece #8
In the present, go to the cave in the southwestern section of Rolling Ridge. Follow the cave until you get to the Goron. Bomb the cracked wall here and you will earn your Heart Piece.
Heart Piece #9
In the present, after you clear the Crown Dungeon, go east of the dungeon and enter the cave. Follow it until it ends, and head outside to go east, then north, and east again. In this screen, play the Tune of Ages to return to the past. Now head to the most northeastern section of Labrynna and play the Tune of Ages to go back to the present, where the Heart Piece will be waiting.
Heart Piece #10
In the present, after you've earned the Mermaid Suit, head to the northeastern part of Crescent Island and dive deep down off the northeastern coast to find an underwater maze. From here, head south until it dead ends, then west until it forks. Take the southern fork and continue westward until you no longer can. From there, just head north and enter the cave to claim your prize.
Heart Piece #11
One Piece of Heart can be found when Maple the Witch bumps into you, sadly the Piece only shows up at random. When she drops her items, make sure you grab the Heart Piece first!
Heart Piece #12
Another random Heart Piece is found in a Gasha Nut. Again, this is completely random, but the best results usually come from a Gasha Tree that has been there through a great part of the game.