What were they doing with this?!

It looks almost like a grenade

Are there any gold/copper/silver plated objects from the same time frame? Because this battery would be perfectly good for that

Suck it, Ben Franklin

@title "Scientists believe the batteries (if that is their correct function) were used to electroplate items such as putting a layer of one metal (gold) onto the surface of another (silver), a method still practiced in Iraq today."

Mythbusters covered this in an episode.