Instructions
Press the "X" button to open your items bag. Select the Explorer Kit to go to the Underground area.
Check the map for treasure. It appears as sparkling areas on the map. Use the stylus to mark the digging area, then press "A" to dig once you arrive.
Tap the stylus repeatedly to collapse walls or dig up items. This will randomly result in a fossil. Pick up the fossil by pressing the "X" button and selecting the "Treasures" command.
Press "X" again to bring up the menu, then select "Go up" to return to the surface.
Go to Oreburgh City and enter the Mining Museum. Give the fossil to the curator inside. Leave the museum and return, and he will give you a Shieldon.