The X-Shaped Jewel is a quest item found within Oracle of Seasons. It is one of the four collectible Jewels, along with the Square Jewel, Pyramid Jewel, and the Round Jewel. Link must collect all four of these jewels in order to gain entrance to the Tarm Ruins.
The X-Shaped Jewel is located on a small island at the south end of the Western Coast. In order to reach the island, Link must use his Slingshot and some Ember Seeds to light the Torch, causing a bridge to appear. On the small island Link can use a Mystery Seed on the large question mark, causing a Mini-Moldorm to appear. After defeating the enemy, a Treasure Chest containing the X-Shaped Jewel appears.