Well, it looks raised but not connected to the rim so not a cud…therefore it must be called an interior die break.
If that spot is raised it’s an interior die break. If it’s not raised but cut into the coin, it’s a small struck through. Either way it’s minor but nice to find.
Abusively polished die . . . makes a normal design element look like an island, as if it doesn't belong.
After reading @ToughCOINS response I looked at a nickel of Jefferson in the same pose. He is 100% correct. That’s the tail end of Jefferson’s hair. The test has been polished away to extend the life of the die.
