Late 1800s Poison Ring (sold)

I’ve never found one of these before.  Usually what people call poison rings are mourning rings, with a compartment for holding a lock of hair.  But this one seems truly sinister.  The compartment is concealed behind the face of the ring, and pops open by depressing one side of the door.  Add the religious imagery on the face, and the whole thing feels downright occult.