I beat the game and now I'm looking for secrets and other things. When you warp to the desert, you find this big hole in the ground that's kind of in the shape of a cone or something. Beside it is this rock and when you go near it, Navi turns green over top of it and you can Z-target it but Navi doesn't say anything. I've used every item I could and I don't know what it is. Could someone tell me?