Fungal reproductive spores vary greatly in size, shape, color, and surface texture. They range from 1 to 100 microns (1 micron = 3.93700787 × 10-5 inch) in diameter—the largest approximately one-tenth the thickness of a dime—with the majority about 2 to 20 microns in size. Yet another comparison is that twenty million 5-micron spores could fit into the space of a postage stamp.