The two alien races first became aware of each other's existence when the Poobs' radio broadcasts were intercepted and returned by the Koozebanians. But because each radio transmission takes eleven years to reach the other planet, generations passed between those first communications and their first expected meeting, which is reported by Kermit the Frog in "Close Encounters of the Worst Kind," a sketch in "Kermit's Story," the first in Roger Langridge's four-issue run of The Muppet Show Comic Book.
The Male and Female Koozebanian Creatures eagerly expect the arrival of the Poobs, so they are doubly disappointed when, first, the Poobs' spaceship lands on and flattens then, and second, it is the Zimmer Twins who emerge from its hull instead.
A poob later makes an actual on-screen appearance in The Muppet Show Comic Book: Muppet Mash. In part 2: "That's a Wrap", Kermit seals the deal for an appearance by Calistoga Cleo with her agent, Mrs. Keppel, by offering free use of a Poob. Later in the same issue, Dr. Bunsen Honeydew invents an Anti-Aging Treatment, with the secret ingredient being a special enzyme secreted from the firrbil gland of a Poob. In part 4, "Curse of the Beaker", Dr. Bunsen Honeydew wants to put Beaker's brain into a robot, offering to put a poob, named Hugh, inside Beaker's head in place of his brain. However, Beaker secretly puts Hugh inside the robot instead.
Whether the Poobs seen in Muppet Mash are the same as the species from Koozebane is unknown. In Muppet Mash Part 4: Curse of the Beaker, Poobs are decribed as Gerbil-like creatures, and share many characteristics with gerbils, including running inside balls and eating gerbil food.