Skull and Strike Menuki

A Skull and Strike orphaned menuki. School unknown, late Edo Period circa 1800

This piece is a bit of a mystery. Aside from the obvious Silver and shakudo construction, the imagery remains an enigma. Overall this menuki is strong and robust, not clumsy.

Is the skull over top of the object or is the skull impaled upon the object? I believe the former to be correct. As to the object itself......what is it? I have seen a matched set of menuki for sale made of copper and they were this exact shape (minus the skull). The vendor said they were "strikes". I don't have a clue as to what a 'strike" might be or what it is /was used for and ANY help would be most appreciated.