The black hardness in the navel may be caused by dirt residue or umbilical cord infection and other diseases. 1. dirt residue: navel area folds more, in daily life, do not pay attention to keep the umbilical cord skin clean, may lead to dirt residue, day after day, can form a black hard phenomenon, it is recommended to use iodine pomade on the umbilicus in a timely manner to clean up. 2. Umbilical cord infection: usually due to bacterial infection caused by inflammatory lesions, if not treated in a timely manner, may lead to a large number of bacterial secretions, thus appearing in the navel black hard phenomenon, it is recommended that the patient in the doctor’s guidance to use iodine pov sterilized, and then the use of hydrogen peroxide and other medications for treatment. When there is a black hard object in the navel, you should go to the hospital in time for examination and treatment under the guidance of the doctor, do not feel free to blindly deal with, so as not to delay the condition.