In the underground, bury a large amount of spheres in one area. The next day, the walls will be full of digging locations for spheres and treasure. Bury at least fifteen spheres that you do not mind keeping buried for a long time to get a huge selection of digging spots. If you keep the spheres buried, the walls will always be full of treasures and spheres every day. Note: Once you deplete the walls of digging locations, there won't be much more in that area forthe rest of the day.