That raises a question to me - if there was a trapdoor, to leave the body in the grave, and allow the removal of the coffin, it'd have to be the same size as the base of the coffin, probably hinged at each side, and opening centrally and how would that be secured during the funeral ceremonies and actual burial? They could hardly rely on the occupant of the coffin sliding a catch across, could they? Anyone seen patent drawings for such a device?