Welcome to CT. If the coin is prior to 1982 it could be a lamination defect on the planchet. This can occur when improper mixing of two (or more) metals together to make an alloy. In the case of a cent prior to 1982, this would be copper and zinc.
Looks to be a bisecting die crack can you post in full not thumb nails the obv. And rev. Of the coin. http://cuds-on-coins.com/rim-to-opposing-rim-die-cracks/
Being a member since 2019 means you must follow Coin Talk, but maybe you don't read this forum on a regular basis. It appears you have a pre-1982 Lincoln cent with a possible lamination issue. Check out some of the well-known cites on errors for more information. http://www.error-ref.com https://coinauctionshelp.com/lamination-mint-error/ https://goodcollector.com/articles/lincoln-cent-lamination-error/ Good luck
Oh, yeah, you might also benefit from this: For the best results, you should post "in focus," FULL IMAGE photos (after you upload your photo, two buttons appear: Thumbnail and Full Image, click Full Image and your photo appears full size on your post and are easily enlarged by clicking on it). Photograph coins on neutral backgrounds like black, grey, or white. Crop out superfluous background so just the coin shows (you can use https://www.remove.bg for free), and post photos with correct orientation so members don't have to turn their computer in some awkward fashion to view it properly. While it isn’t always necessary, it is nice to show both the obverse and reverse, even if your question is just about one side. Members can often give more valuable information having both sides to evaluate. Add close ups of areas you have questions about and make your questions as definitive as possible so we know what you are asking for. And try to have the best lighting possible to show the most favorable photo of the coin. Hope this helps in the future. Good luck.
Can't say for certain based on those pics (need a full shot of the obv), but it looks like corrosion damage. The line looks recessed, not raised as would be expected from a die crack. Whatever caused the stain ate away at The metal, particularly at the edge of the contact (edge of the stain), IMO A pic of the full obverse should help clarify if the feature is raised or recessed and if it could be something from a lamination defect (I don't think so, but can't rule it out yet)
I can’t quite tell as there are no photos of the entire obverse and reverse but to me, based on those small thumbnails, it may a defective planchet. A die crack would be raised and I’m not seeing that.
I am going to say the defects on your coin was cause by environmental damage. Looks like corrosion that has been removed from the area in question.
