1923 Lincoln Cent So Old It's Got Wrinkles.

That is part of the die wear pattern. These will appear behind the devices. Because they are on the fields of the die. The fields of the die are outside part of the die. They die is a negative, the coin is a positive. So what is raised on a coin, is incuse on the die. What is raised on the die, are incuse deep into the die. When a die is polished, the outside part is affected. (the fields) the devices are not affected, until the fields get polished several times. Each polishing removes part of the field:

When the die is polished, the sub devices are the first to go, and also note on the above, the devices are tapered. So the more the field is polished, the shorter and thinner the devices become. Often clashes happen that require a light polishing, but if a Feeder Finger Damage event happens the die has to be polished deeper. This removes more the field and the devices also get affected.

When the die is polished the flow lines that you see are removed. But they some back as the polishing is just a die event. Soon it needs it again, and again more of the fields go away and the devices get thinner.

So what you are seeing on your coin, is like wrinkles to a senior. Part of the die aging process. (But we don't have our wrinkles removed by buffing off or skin) LOL

CoopHome: What are the wrinkles of the fields and why are they behind the devices?

I've been spending more time of explanations lately and adding it to my CoopHome page. So when I need to explain this again, I look up that information and then post the link to that information. Spends up by time and allows me to do this on more comments. I'm glad it helps you. I reached my goal today.
Look for more new I items on that link. I call my it my "Answers to questions, before you thought of the question." these are listed as questions on the links on that thread of many threads put together. It is the beginners guide to coin collecting. Looks like I came up with a title for a new book? (but getting to old to put all this information together now)

Yes, yes--die deterioration. Nice example.

I agree - Die Deterioration. the 'wrinkles' you see are 'radial flow lines' of the metal from a worn die.