From the rim above the TR in trust to the rim below Abe's vest it looks like the strands of shipping tape. As far as what's behind the eye - it looks like a staple, however it is not attached to the coin. Also on the reverse it looks like the outline of the memorial is doubled. Thanks: Lou
Just a weird worn die effect. Not a struck through anything. Some clues is the Ridge Ring and die deterioration doubling on the last digit on the date.
Ask yourself when the master die was hubbed, how could doubling appear on both sides of the memorial going in opposite directions. As stated above, die deterioration is clearly evident with the pronounced ridge ring and the spreading towards the rim of the outer devices.
It’s just damaged and starting to show zinc rot. You can see a ridge ring in its early stages just beginning to form so that should tell you it’s minted by a worn die.