Glass bird

A Pearl Bird appears in the Game Boy Advance game Wario Land 4. It is a strange, green bird with small wings, and a mouth that can expand to a large size. It is only seen in two Puzzle Rooms throughout the game, one in the 40 Below Fridge, the other in Crescent Moon Village. It doesn't harm Wario in any way, but actually helps him by spitting out glass spheres which Wario can catch and throw at two "!" Buttons that would otherwise be out of reach. These "!" Buttons, when hit, will change corresponding colored blocks from solid to transparent, allowing Wario to pass through them to reach a Diamond. The challenge is to make both colored blocks transparent at one time, so that the way is cleared and Wario may reach the prize.