What exactly IS this?

This neat fixture lights our home office. As do many of the fixtures I've acquired, it has a semi-interesting story behind it: I remember this one as a 12 year old in the kitchen of a since-demolished house some friends were renting. I also know the actual owner (at that time) of that house. (It was sold and torn down later). Anyhow this isn't the only fixture from that house: I also saved a nice 1970s Sears 2X40w shoplight from there with a full power GE Bonusline HPF rapid start ballast. (Which currently functions as a plant growlight). I saved the shoplight long before the house was torn down but the above lamp was saved during the teardown actually.