Hello, I had this for as long as I can remember and I have no idea what could it be and how do I treat it.
It's called keratinization and its caused by leaving your glans(head of penis) exposed to the air, clothes, dry hands etc. Anything that can irritate it physically. Circumcised men get this all over their glans but in a much greater extent. You can treat it over time by leaving your foreskin in place and not doing anything that causes it to feel irritated. That type of skin there is a mucosa, so try not to do anything to it that you wouldn't do to your eyelids. Essentially, it's a callus so if you were to reduce any friction or air exposure it will lessen over time.