One of Man Ray's Perpetual Motif objects, Object Indistructible succeeded the Object to be Destroyed, which was published with the following instructions:
Cut out the eye from a photograph of one who has been loved but is seen no more. Attach the eye to the pendulum of a metronome and regulate the weight to suit the tempo desired. Keep going to the limit of endurance. With a hammer well-aimed, try to destroy the whole at a single blow.
The original Objet was in fact destroyed in 1957 when students followed Man Ray's instructions to the letter and smashed it to pieces.