Well! This week you were certainly intrigued and so many good guesses but no one got it. The image is of a padlock and key found in York dating from the Viking era during the Coppergate Dig – something I looked forward to seeing most summers now I come to think about it.
The barrel shaped lock is opened by inserting the key into the opening at the end. I think that the action of fitting the key compresses springs to release the shackle of the bolt. The lock is a high status item in its own right.