How you know if what you’ve found is Mold
Black, grey-brown, grey-green, white & orange spots, or even pink or purple splotches if growing behind vinyl wallpaper. Stachybotrys is commonly a dark, slimy, greenish-black mold.
By sending a sample of the biological growth to a lab, they may be able to determine whether it is mold, and what species of mold. You would need to use a surface sampling technique that allowed the species to be identified .
Other Signs of Mold Present