The "Seifenblasen" (Soap Bubbles) were weather balloons with a metallic coating and carrying metal strips of various lengths to confuse Allied airborne radars. When spotted in the daylight sun or moonlit night, the reflecting Seifenblasen gave the appearance of a Feuerball weapon. They were derived from the Kriegsmarine’s U-boat secret weapon “Afrodita” (Aphrodite) anti-radar balloons, used as a decoy against patrolling Allied anti-submarine aircraft. Since the Afrodita balloons worked with some measure of success, the ground-launched Seifenblasen were developed for use against Allied bomber and intruder aircraft radar. Confused by the WNF Feuerball weapon, the AEG Kugelwaffen weapon, and the lone Kugelblitz disc craft weapon, the Siefenblasen balloon was lumped in with the other Foo-Fighters. See links for pics and explanations.

http://discaircraft.greyfalcon.us/picturese/aeg3.jpg http://discaircraft.greyfalcon.us/WNF%20Feuerball.htm