what is it

I would guess either a flare launcher or some sort of evil "trap."

On PBS I think, "History Detectives" someone had a weird ball device with a trip mechanism, it was concluded to be a deal you put on top of a casket to prevent grave robbing. Evidently when medicine really started to "take off" there was a shortage of cadavers for medical dissection, and people would dig up bodies and sell them to labs