A black spot like a mole suddenly grows on the tongue, which may be related to petechiae, pigmented moles, diet and so on. 1. Petechiae: If the tongue is subjected to trauma or localized friction, capillary rupture may occur and black spots may appear. 2. Pigmented nevus: It is a benign neoplasm composed of nevus cells, which may also grow on the tongue. 3. Diet: such as consuming mulberry and other foods may lead to blackening of the tongue, which usually fades away slowly after a period of time, or small black spots may appear if the fading is incomplete. It is recommended that people who have a black spot on their tongues that looks like a mole should consult a doctor in a timely manner to clarify the cause, and if treatment is needed, standardized treatment should be carried out under the guidance of a doctor to avoid delaying the condition.