Yes - exactly. And I think the string is dried up in the dried blood - covered in the dried blood, and that is why you can't see it.
Ok after two hours cut it off, you don't want that string to go into her body, it's just temporary so that she can be free from the shell and have better moveablity..
Might even want to check it in an hour. Perhaps the blood was just excess blood still left in the cord coming out where you had the string..
Once that cord shrinks up go ahead and cut that string off...