This vacuum tube, found at Dead Horse Bay, is filled with water. The liquid seems to be sealed in there now. I don't know why. When I first brought it back to the home lab, the water was gray, but the murk has now settled, giving us the drowned civilization look.
Fun facts for kids: the first computers used vacuum tubes, and were, consequently, as large as rooms and as powerful, computing-wise, as one of today's automatic coffee makers.