Poob

The Poobs are a race of famously peaceful sapient beings native to planet Poobatron. They are the Koozebanians' closest galactic neighbors and the two species have been communicating with each other from many generations. Though the two species have yet to meet each other in person.

Appearance
While we still have as of yet to see a Poob we know based on the world of Dr. Bensen Honeydew that they are small enough to fit inside Beaker's cranium as he offers to place Beaker's brain into a robotic body and put a Ploob, named Hugh, in place of Beaker's brain to keep his body active (The Muppet Show comic Book: Issue #11 Curse of the Beaker). Beaker however tricks the Doctor by placing Hugh inside the robot body. Dr. Bensen Honeydew states that Poobs resemble Gerbils and have a habit of traveling inside balls and can be sustained on gerbil feed.

Medical Applications
According to The Muppet Show Comic Book: Issue #11 Curse of the Beaker an anti-aging treatment utilizing an enzyme produced by a Poob's firrbil gland has been devised by Dr. Bensen Honeydew.

Source

 * The Muppet Show Comic Book: Issue #1