(you-low-clay-dee-um) - contaminant, found everywhere.  Can grow indoors on various materials including paper, but requires more water than some other molds.  It is reported to be a major allergen.

 is frequently isolated from air, cellulose materials, decaying or dead plant materials, dust (especially mattress dust), gypsum board, soil, paper, paint, textiles, water from humidifiers and wood.  [..]

This commonly found mold requires a great deal of moisture to survive indoors. Isolated from dead plants and cellulose materials. Found on textiles and other organically bound substrates. 

species A rapidly-growing fungus that produces a brown, or black colony with a dark reverse, within five days, when incubated at 25oC (77oF). The hyphae, conidiophores, and conidia are pigmented olivaceous-brown (dematiaceous). It is found worldwide and is very common. It can be isolated from the air, plants, rotten wood, paper, textiles and soil. [..]