Mucor is a rapidly growing fungus that is usually dark gray or light olive gray when grown on typical laboratory media. One colony can easily cover a 15x100mm petri dish in four days. It is easily recognizable microscopically by its tall (up to 2 cm) needle like sporangiophores and large sporangium. Mucor Mold has worldwide distribution and is often found in hay, stored seeds, horse manure and house dust, regardless of geographical location. It is also frequently found in air samples from indoor environments. Accumulated dust in HVAC systems and poorly maintained carpeting may contain high concentrations of Mucor spores. Mucor is a rare opportunistic pathogen.