He appears to be a skull. He has big pitch black eyes, a pitch black nose, lower teeth, and black streaming from his eyes, and is able to open his mouth wide.
Mike is in the center of the office. If you click him, he will open his mouth for about a second. Occasionally a gray pizza will come in from the left of the office, when the pizza is about to touch Mike, you must open his mouth to let him eat it, if you don't, you will fail to feed him. Failing too many times will result in death.