Fredric Brown

The mysterious Outsiders have skirmished with Earth's space colonies and starships. Their vessels are found to be faster and more maneuverable, but less well armed. There have been no survivors of the small raids on Earth forces so Earth has no information about the Outsiders. Fearing the worst, Earth builds a war fleet. Scouts report a large armada approaching the solar system. Earth's defenders go to meet them. All indications are that the two fleets are evenly matched.Bob Carson is the pilot of a small one-man scout ship on the outskirts of the fleet. While engaging his Outsider counterpart in battle, he blacks out. When he awakens, he finds himself naked in a small enclosed, circular area about 250 yards (230 m) across. Other than vegetation and blue sand, he sees in the distance only a red sphere about 1 yard (0.91 m) in diameter. The sphere turns out to be an Outsider, with several dozen fully retractable thin tentacles to manipulate objects. Based on its method of movement, Carson labels it a "Roller".