Scanning electron micrograph (SEM) of Rhizopus stolonifer. Black bread mold. Mycelium, sporangiophores and sporangia. Spores circulate freely in the air, and upon landing on a favorable surface, germinate a network of hyphe (threads) that absorb nutrients for growth and reproduction. This fungal network makes up the mycelium. Spores develop in sack like structures called sporangia. The walls of the sporangia then break down from the pressure of the maturing spores, releasing them into the air. Magnification = x350 at 8x10 inch print size.