Although we’re better off knowing it, no one likes to hear they have bad breath. The gross morning breath most of us wake up with is normal and disappears after brushing our teeth, flossing, and cleaning our tongue, but what if the bad breath persists? Lingering bad breath, also known as halitosis, could be the side effect of a grain-sized problem — tonsil stones or tonsilloliths.

In the video, “What Are Tonsil Stones?,” Gross Science host Anna Rothschild explains it is the bacteria and other microbes that feast on the globs of organic matter and sulfurous waste products in crevices of the tonsil that produce the deeply unpleasant odor. These tonsil stones often form if you’ve had repeated bouts of tonsillitis, or if you have rather large tonsils with lots of nooks and crannies. Moreover, you might not even know you have them because they can grow behind the tonsil where you can’t see them. A 2013 study published in the journal Dentomaxillofacial Radiology found tonsil stones are a widespread affliction, as it found out of 150 CT scans of people’s heads, about 24 percent showed signs of them.

There still exists much debate as to how they begin to form, but it is known dead cells, mucus, and food get trapped in the crevices of the tonsil and harden, or “calcify.” The stones usually range from as small as a rice grain to as big as a pea, but they rarely pose a health threat. However, if they get larger, they can cause sore throats, ear pain, a sulfurous odor of bad breath, and even difficulty swallowing. In a 2008 case report, doctors in India removed a giant tonsillolith that was making it painful for the young patient to swallow.

Tonsilloliths can be permanently resolved by having the tonsils surgically removed, but there are less drastic remedies that can force the stones out. Rothschild explains some people recommend gargling with salt water or other special mouthwashes, flushing them out with a water pick, or popping them out with either your finger or a cotton swab. Tonsil surgery should be considered if tonsil stones become severe and interfere with your daily life.