Zelda Spirit Tracks Hidden Tasks/Games Part #9

After you get a certain force gem, a track appears leading to the top left corner of the snow realm. Go there and there should be white wolfs and a cave. Get to the cave and solve the puzzle there and a treasure chest appears. A force gem is not in it, it's a bid crystal thing that you can sell for 2,500 rupees, so it's probably worth about 5,000 rupees. You probably have never seen it before because it wasn't in any of the other games, there is one more in the game.