Wonder Egg
From Bulbapedia, the community-driven Pokémon encyclopedia.
The Wonder Egg is an item found at the end of the Surrounded Sea along with 3 Deluxe Boxes. It goes into the Treasure Bag until the player leaves the dungeon. The next morning, the Wonder Egg hatches into a Manaphy, and the Wonder Egg cannot be collected again. Template:Gamestub
