Magma Shard

Magma Shards are key items found in Golden Sun: Dark Dawn. They are golden shards that are found once the Mountain Roc is defeated. Magma Shards are described as "A piece of a volcano's power" by the first tablet within the Belinsk Ruins. This tablet is located in the same room that contains the first pedestal to put a Shard on.

Story
Magma Shards are first mentioned by Tret and Laurel as a necessary item for exploring the Belinsk Ruins. The two describe the Shards as a fragment of the Mountain Roc's power. After Matthew's party defeats the Mountain Roc, they notice that one of the shards fell out of the Roc's mouth. After entering the Roc's interior they find four other shards, as well as a Magma Orb, a fully formed sphere of the Roc's power. After a confrontation, the Sanan prince, Ryu Kou would take one shard, the Slap Glove and the Magma Orb in Matthew's possession, with the intention of using them to explore the ruins himself.

Matthew's party would take the remaining shards and enter the ruins. They find that the shards are used to activate special pedestals. Afterwards, the layout of the platforms and structures in the ruins would change. After using one of the shards, the Adept's find that their initial route has been cutoff, forcing them deep into the ruins.

Uses
All of the Magma Shards are used to navigate the Belinsk Ruins. The first Shard that is used will open a wall to reveal a door. The second Shard will make pillars rise from the bottom to allow the player to reach a chest as well as access to the next room. The third Shard will also open a door into the Belinsk Castle, revealing Sveta as well as reveal a new path deeper into the Belinsk Ruins. The fourth Shard will power up gears after the second gate has been opened.

Trivia

 * There is a fifth pedestal in Belinsk Ruins for the fifth Shard, apparently meant to provide an explanation for the Sanans' entrance into the ruins. While the player can potentially access the room, the pedestal will be unusable.