Wolberg sorted his subjects into these categories: vegetable, animal, mineral and familiar objects. Under the microscope went all sorts of things! Here are a few examples: pollen, algaes, airborne seed, fungus, bat hair, butterfly wing, rabbit esophagus, turtle tongue, cast steel, copper-zinc alloy, hard chromium, silk threads, cellophane tape, mustard, cotton, wool, bread, toothpaste and the print on a postage stamp.