Strike Through With Embedded Debris?

I thought I read an article once by Mike Diamond that talked about debris sometimes remaining in the coin after a strike thru. I was wondering if this might be an example of that phenomena and I have pointed out the area I am referring to. Now, I have noticed that there are other indentations that look shinier than the surface of the coin which usually indicates PMD, however I was wondering if it could be possible for those indentations to have had embedded debris in them for most of the life of the coin and, with circulation wear and tear, sometime along the way fell out. To the naked eye it looks like there is something lodged in the indent. What do you all think? All opinions are appreciated, thank you.