The Malusian Blob

Space shuttle astronauts unwittingly load an alien chemical blob into their cargo bay (assuming it to be space junk). The blob starts eating metal and the astronauts call for help. Batman, Robin and Back Vulcan zip out there and rescue the astronauts. Assuming the blob burned up in the atmosphere, they return to earth, but then the blob reappears and after some failed attempts, they figure out the creature has a problem with sugar.

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S07E19 - Attack of the Cats