Hello, You may have mineral or calcium deposit buildup. Veins and saliva ducts can get stones similar to kidney stones. Tissue tags or excess fibrous tissue can appear firm and be the result of irritation. These are common occurance in the mouth. They can be monitored or removed if causing a problem. Small stones can be gently dispersed with massage from the duct. Rinse with warm salt water. Greater concern should include symptoms with pain and sudden change. Location and a greater amount of detail may help with suggestions. A clinical exam with your dentist or physician would be helpful to rule out a tumor, cyste or other growth. Pictures can be submitted. Please read instructions on the web site or call Healthcare Magic customer care for assistance. Thank you for your inquiry.