Just for future reference it would benefit you and us if you could give us a full image of both sides of the coin. Based on your photo all I'm seeing is PMD and maybe a few plating blisters. JMO
That raised ridge is formed by a deteriorating/worn die. It is not an error. It is very common on zinc cents but does appear on other coins as well, just not as often. In its latest stages it get REAL impressive.