

Not all fungi are attractive or useful and I've posted a few previous examples of some onerous ones. The several species in the genus
Stachybotrys are probably very beneficial to nutrient cycling in the wild, but when a house becomes infected with the critters, there can be serious economic and medical problems.
Stachybotrys sp. are able, in mild temperatures and with humid conditions, to digest and breakdown materials with a high cellulose content. When this happens to woody debris and other dead vegetation, this fungal activity liberates materials held in the plantstuffs making them available for use by a host of other organisms directly and indirectly.
In a building made from plant material (framing, plywood, fiber board, some paneling and cellulose rich insulation)
Stachybotrys may get a foothold and thrive, for a while hidden, and then "blossoming" to exposed surfaces where it is virtually impossible to eradicate except by removing entirely the infected material. While at work,
Stachybotrys may release byproducts of its decay process that are toxic (mycotoxins) to humans and and other animals. Plus the abundant production of spores wreaks havoc on on some individuals as a powerful allergen.
Controlling humidity, using treated building materials that contain cellulose and being vigilant may help keep
Stachybotrys out in the woods where it belongs (and probably prefers to be).