don't disturb it! if it is surface mold, it can be wiped off; if it is inside the walls, it means the air is full of the mold seeds flying around, and the apartment is beyond repair - it will be a mold house forever. if you breath the mold long enough, such as years, you end up with immune and psych problems. Don't try to kill it - it's a million year old organism that isn't getting killed, it can only be removed with hepa vacuum, scraping, soap and water, etc.