Fishing line
A fishing line was part of the equipment used in fishing. In addition, fishing line could be used in emergencies to stitch open wounds closed.
At the age of 16, Hugh Culber was hiking along the cliffs of Cabo Rojo when the path he was walking on gave way, causing him to fall 15 meters and puncturing his shoulder in the process. A doctor named Kashkooli rescued him, stitching Culber's puncture wound closed with fishing line. According to Paul Stamets, he would have bled to death without the intervention. (DIS: "The Sound of Thunder")