I came across this 98 Penny with a odd mark underneath the first Nine it looks like its supposed to be a MM but its at an odd angle as well. And I know my pics are not the greatest at all, I don't have a ton of experience with photographing coins but I am learning and working on a better solution. But these are the best I can do for the time being. Any suggestions on what this mark could be would be great.
Based on your photos it appears to be a plating blister you can see other's as well on the coin.IMO Dave Ps. Don't forget to check the reverse to see if it's a WAM.
Either a plating blister or a hit which explains the straight line under both nines which pushed a small amount of metal upwards. Either way, it a spender.
Your 1998 Cent was minted at the Philadelphia Mint They don't use a Mint Mark and Cents. Only once which was for last year 2017. What you are seeing is a simple plating issue. Nothing to do with a strange Mint Mark. Most likely a Plating Bubble.