“Found in a thrift store: a porcelain plate with a metal bottom. On its side, there is a pipe. What could this be?”
Answer: “It’s a plate warmer for toddlers. Through the pipe, you add hot water, close it up, and it keeps the food warm while the kid eats. As a bonus, the image depicting the characters is put there so as the kid gets closer to finishing the meal, the image is revealed.”