The Thermortian Sand Worm was a creature whose internal organs would turn into sludge if fed water. When trapped in a labyrinth, Romana II was asked the riddle, "Feed me and I live, give me drink and I die", by Taureau the minotaur. She gave the answer as a Thermortian Sand Worm, but Taureau was expecting the answer fire. (COMIC: The Forgotten)