Beach Ball Aliens are a gas-based life-form from an unknown world.
Beach ball aliens are so named due to the fact that they resemble a common inflatable beach ball with webbed feet. Much like a beach ball, they are filled with gas, and burst if their skin is penetrated.
Nothing is known about the origins of this species. All that is known is that at some point the crew of the decaying spaceship Dark Star encountered one at an unknown point. One of the crewmen, Sgt. Pinback, thought it was "cute" and decided to keep it aboard.
Unfortunately, after several months on board Dark Star, the alien attacked Pinback while he was trying to feed it, and escaped from the room where it was being held. It proceeded to run around the ship, constantly eluding Pinback. After an incident in which Pinback nearly died getting stuck in a broken elevator, he finally resorted to stopping it with a tranquilizer. However, the tranquilizer ultimately caused the alien to burst, apparently killing it.