Key Shards are quest items from The Legend of Zelda: Twilight Princess. When combined, these three unique shards form the Boss Key to the Goron Mines. In order to obtain the shards, Link must travel through the Goron Mines and speak to three of the Goron Elders. They are Gor Amoto, Gor Ebizo, and Gor Liggs, who are located in three secluded rooms.
Interestingly, this is the only Boss Key in the The Legend of Zelda series to be broken into three shards.