The Tequila Mockingbird.
Mysterious bird-shaped artifact reputedly worth a fortune in diamonds, rubies and pearls, named for the city of Tequila, Mexico, where it was first acquired by millionaire art collector Conrad Parmenter.
10 years later the Mockingbird was stolen but reappeared 12 years after that in Beirut before disappearing again. It was finally recovered in 1969 by CONTROL agents Maxwell Smart and 99 in the Mexican village of Mira Loma.
[Episode #103: "Tequila Mockingbird".]
Although the comparison is not explicitly made, the Tequila Mockingbird is highly reminiscent of Dashiell Hammett's Maltese Falcon - a fact that Max, as a fan of the movies of Humphrey Bogart [Episode #119: "And Baby Makes Four"], would no doubt be aware, having made specific reference to it during his and 99's visit to Casablanca two years earlier [Episode #36: "Casablanca"].