I think this is a very thin
Cud, but I am interested to hear opinions from people here since it's such a long and thin sliver. Whatever it is, clearly the gutter of the die has been altered in some way as it is off-round on the inside with extra material suggesting a die break. Perhaps a long die dent, though? One thing I do find strange is that whatever it is, it hasn't raised the material around the rim of the coin, only the material inside the bounds of the gutter itself.

