3. Hairy Tongue
The human tongue is covered with a protective layer of dead skin cells called keratin that normally slough off when we eat or drink. Keratin is the same stuff that our hair and fingernails are made of, so when it accumulates it can breed bacteria and resemble, well, moss on rocks. Hairy tongue is usually caused by irritation from smoking or drinking hot beverages and a tongue scraper usually takes care of the problem.
