This delightful little item is called a "ring coffin" and its intent is to facilitate that final symbolic death of the relationship and burying of the past; the intent, as stated by the creator, is to help with closure when a relationship ends and help the angry person act out their feelings, then, in principal, move on.
The full story regarding this "interesting" item is available here. I see a possibility for a spin off of this....how about a hatchet coffin...when you wanna "bury the hatchet"? Hmmmm...
Till later, much love to you....
v