Sealed for an unknown span and found again — as tradition absolutely requires — by four teenagers following a dog named Robot, the cave preserves fifty-five painted panels spanning some twenty thousand years — from a notched baboon bone to a beast that guesses the next mark — two intrusions of disputed date, and some three hundred lesser figures crowding every wall and ceiling. The pigments are red ochre, charcoal, kaolin, and a green that should not exist. The torch was found at the entrance, still warm. Visitors are asked not to feed the Perceptron. Remember to look up.