Picture of Tonsil Stones
Tonsil stones, or tonsilloliths, are hard pieces of debris comprised of mucus and bacteria that get trapped in tonsil crypts. They can contribute to bad breath and may cause pain or discomfort. Although they may cause symptoms, tonsil stones are not dangerous.
Text Reference: Journal of Clinical & Diagnostic Research, vol. 7, 2013: "Tonsillolith: A Panoramic Radiograph Presentation"