The San Francisco Mint used two different mint marks on cents in 1947: the Sans Serif S and the Serif S. There are better photos on thelincolncentresource.com, but the ones I am attaching are the best I can do with what I have at hand. The first is a coin with normal Sans Serif and the second is a coin with normal Serif. But sometimes one comes across a coin with a mint mark that does not seem to fit the mold. The next photo is of a coin with what looks like it could have an inverted Sans Serif or perhaps a Serif that has been altered by die or circulation wear. Note that the last coin has a convenient die marker, a dot just southwest of the 1. The story got more interesting when I found an earlier die state example with a sharper dot and mint mark. If you look closely at the mint mark, you should be able to see what looks like a Serif S on top of a Sans Serif S. Could the double punching account for the unusual appearance of the mint mark? Is it possible that an inverted Sans Serif was punched first and then a mint worker tried to correct the mistake by overpunching with a Serif? The Serif on top on the coin would mean that it had to be on the bottom (deepest) on the die. Perhaps an MS, EDS example would reveal more of the story.
where you have the red arrows it looks to me like something may have bumped against the mintmark and pushed the small area down.
The area in the bottom loop is more round than the oblonged upper loop. Once you get used to seeing it, it comes natural...