Tonsilloliths, also known as a tonsil stones, are clusters of calcified material that form in the crevasses of the tonsils. While they occur most commonly in the palatine tonsils, they may also occur in the lingual tonsils. Tonsilloliths have been recorded weighing from 300 mg to 42 g. They are composed mostly of calcium, but may contain other minerals such as phosphorus and magnesium, as well as ammonia and carbonate.Protruding tonsilloliths may feel like foreign objects lodged in the tonsil crypt. They may be a nuisance and difficult to remove, but are usually not harmful. They are a cause of halitosis (bad breath).