Strange defect indeed, though I am fairly certain that's a dent that wiped out the missing portion of the date. The coin took a hard hit. Others will correct me if I'm wrong.
I agree on the hit....of some type, though I have no idea what. The D appears a little "doubled" also. It's just one of those oddities you put in a bucket and save for poor man's Show and Tell.
The D isn't doubled. It also took a hit giving it the squashed appearance. You can see the other hit under the visible 9 in the date
Yes, you are correct, Sir. Of course it isn't doubled, thus the word "appears" and the " " quote marks around the word doubled. I'm referring to the line, or silhouette, around the D , which many people, including myself when I first started searching coins, believe to be doubling.
That's the copper plating splitting apart, a fairly common occurrence on our Copper- Plated Zinc Cents. The Mintmark is not doubled, it's split copper plating that makes it look 'doubled'.
Someone probably whacked it twice with a small hammer considering how the first 9 was obliterated though still slightly visible into the depression. My daughter does artsy things with coins. I'll refrain from putting everyone in heart attack mode by describing all the things I've seen. I have posted some minor artsy coin things in the past.
" Does anyone know what caused the date to look like this? " I blame the opioid crisis. It's the hip thing. Opioids - drugs that make you look like Ron Howard as a young boy.