Here, in the National Museum of Scotland, you can see a very strange object: a coffin collar or a collar for the dead. The coffin collar was an iron collar often fixed to a piece of wood. It was fixed around the neck of a corpse and then bolted to the bottom of a coffin. Most common reports of these collars being used came from Scotland around the 1820s. These collars were made to thwart grave robbers. The grave robbers were students of human anatomy. Legally, only the bodies of executed criminals could be used to study anatomy. But the demand was bigger than the supply.
Source: Eric Weiner, 2016, Geography of Genius, 146
City of Edinburgh