It is an ultrasonic remote (probably from Zenith) c. 1970. The buttons ring little chimes inside the unit each one tuned to a different frequency (but too high to hear). The screen on the top is so that the sound can get out. It does not need batteries because the chime is rung by the pressure you apply. It is an early example of energy harvesting! After this model Zenith used an electronic version and then switched to IR.

Check out the Douaumont Ossuary on google. 130,000 French and German soldiers bones are collected there from the Verdun battle field. - Charlie