In the Pokémon Omega Ruby and Alpha Sapphire games Mirage Spots are places where you can go to gain extremely rare Pokemon that other wise would not have shown up. In Hoenn these Pokémon include everything from Legendary like Reshiram (Omega Ruby) and Zekrom (Alpha Sapphire) to common Pokémon like Purugly. These locations also house the fossils of Pokémon like Kabuto (Omega Ruby) and Omanyte (Alpha Sapphire) and also sometimes you can find special items that would not appear anywhere else Shards of varying colors (e.g. the Red Shards and Green Shards).