Yes the black thing opens, it is just a rubber stopper and the jar is a one gallon jar from one of the big box stores. I cut the the center of the handle out to provide a small opening that I could easily open and close to let gnats, etc in but keep the humidity up.
I used a carbide hole saw that I had for tile to make the hole. It is a bit rough, but no sharp edges and functional. This picture is of the opening.
