The presence of mold usually implies decay, although some molds are used deliberately in, for example cheese-making, and for the production of antibiotics.
The numerous spores released by mold does not cause direct harm in humans, but the hyphae grown from those spores could attach to cells along the respiratory tract and cause problems in those with weak immunity.
Use do-it-yourself mold test kits or the Scotch tape lift sampling technique [explained in the mold test kit section of Mold Mart] to test any visible mold growth so that you can send the mold test kits to a mold laboratory for analysis and mold species identification.
Also, use mold test kits to mold test the air of each room, attic, basement, crawl space, and the outward air flow [if electricity is on] from each heating/cooling duct register for the possible presence of elevated levels of airborne mold spores, in comparison to an outdoor mold control test.
Severe toxic mold contamination growth beneath the floor board in the cabinet under the kitchen sink.