X-Shaped Jewel

The is an OoS: in.

Location and Uses
The X-Shaped Jewel is found on an island off the Western Coast. To reach it, Link must shoot an Ember Seed with the Slingshot to light a OoS:, creating a bridge. Then, he must use a Mystery Seed on a rock found on the island, which reveals the OoS:. After defeating him, a Treasure Chest holding the X-Shaped Jewel will appear. It is used in conjunction with the other three Jewels to open the door leading to Tarm Ruins.