While exploring the Great Dungeon in Pokémon Brilliant Diamond and Pearl Shing, you'll encounter several Diglett and Dugtrio popping up from the ground. These Pokémon are among the biomes where Pokémon spawn for these areas. They also disappear when you enter range and when you get close to where they were, they leave little sparks that you can collect, increasing the number on the left side of the screen below the map. How does the Grand Underground Diglett bonus work in Pokémon Brilliant Diamond and Brilliant Pearl, and what does it do?
These are essentially building an added bonus for you. The bonus has to do with minigame fossil mining that you can do while in the Grand Underground. Fossil mining sites are the glowing orange icons attached to the walls throughout the Grand Underground. When you find one of these locations, approach and interact with them to start the minigame. When you complete this minigame, the higher your bonus, you will have a better chance of finding higher quality Statues that you can place in your Secret Base, such as Shiny and Legendary Statues.
Statues in your secret base increase the chance of specific types of Pokémon appearing in the spawn area of the Grand Underground. We recommend creating secret bases if you are looking for specific Pokémon in the Grand Underground during your Pokémon Brilliant Diamond and Brilliant Pearl adventures.