The Roof Cleaning Institute Of America Training & Certification Forum
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I was searching Google, and found this http://www.kaiscience.com/photo_archive.php
It says you must have permission to use these pictures, but maybe if you asked, it would be ok ?
Regardless, it shows molds, and it's  SPORES !!!
This educates the customer, and provides an easy up sell to clean ALL the property 
A VERY interesting web site, more pages of interest on it too.