From the Super Mario Wiki
The Birdo Ray is a large, seemingly unstoppable superweapon and an extension of Darth Koopa's Koop Star. Despite its name, the Birdo Ray does not resemble an actual Birdo; instead, it is named for being a cannon that can fire an egg-shaped missile. The Birdo Ray is also a reference to the Death Ray as a nod to the episode's theme. The missile, if it hits a planet, covers the surface in a yolk-like substance, presumably destroying life on the planet.
The Birdo Ray is featured in The Super Mario Bros. Super Show! episode "Star Koopa", where Darth Koopa threatens to destroy the Mushroom Colonists' Planet with it unless they surrender their planet to him. After capturing Princess Toadstool, Darth Koopa shows her, as well as Mario, Luigi and Toad, a simulation of the Birdo Ray destroying the Mushroom Colonists' Planet, implying that he wants Princess Toadstool to order the Mushroom colonists to surrender.
As Princess Toadstool refuses to surrender, Darth Koopa orders Mouser to activate the Birdo Ray, which fires after a thirty-minute charging time. After narrowly escaping from Koop Star, Mario's group makes it to the Mushroom Colony with only fifteen minutes left until the Birdo Ray is set to go off. Obi-Wan Toadi explains that the only way to stop the Birdo Ray is for someone to penetrate Koop Star in a Mushroom Starfighter, so that they can disable it manually.
Mario and his friends agree to help, and after fighting off enemy Stormtroopa Starfighters, Mario succeeds destroying the foundation of Koop Star with a Bob-omb. As a chain reaction, Koop Star as a whole exploded, taking the Birdo Ray with it, just as it has finished charging.