The Hummingbird Egg is an item found in Chapter 2 of the [[GameBoy Advance|Game Boy Advance]] game Mother 3. It is first referenced by Wess when he tells his son Duster to find a shiny object in Osohe Castle at the beginning of the chapter. When Duster returns with the Noble Spitoon, Wess becomes enraged and goes to the castle to try to get it himself. When he finds it with the help of Duster and Princess Kumatora, he describes it as "secrets wrapped in secrets" that he had to hide from falling into the wrong hands (which is now the Pigmask Army and their leader). He then criticized Duster for not being able to find an object that smells so strongly of secrets. Some Pigmasks then try to enter the room by ramming a Clayman into the door, so Kumatora takes it off of its stand. Wess points out that he set up traps to protect it as they suddenly fall through the floor and into the moat. There they must fight the Oh-So-Snake, but the moat is drained after the fight, washing them away. Wess and Kumatora wake up on the riverbank in Tazmily Village, but Duster and the Egg are nowhere to be seen.
In the events of Chapter 4: Club Titiboo, Kumatora, Lucas, and Boney find Duster as the bass player in the band DCMC but with an afro wig under the name Lucky. They realize that he had amnesia, and his only memory is of waking up with the Hummingbird Egg, and, sensing it was important, hid it in a dead Clayman near Thunder Tower. The party then finds the Clayman, but when struck by lightning, it comes to life (although malfunctioning, such as running around erratically and backwards). After finally tracking it down at a dump, they must fight a scrap metal boss called the Forlorn Junk Heap. The party finally gets the Hummingbird Egg and the chapter ends.
In the final chapter, while exploring the New Pork City sewers, the party encounters Leder, the town bell-ringer who explains that the residents of Tazmily Village were once part of a larger world and that they had to erase their memories (except for one; Leder himself), and that the Hummingbird Egg contained the secrets of the previous world.