Wire Under Tree Bark
I just noticed a wire (probably used to hold a hammock}
Certified GKH Gardening Expert
This is quite common, and usually not much harm to the tree. In fact, it would do more damage to attempt to remove it! If it becomes an eye-sore, it will not hurt to trim it off level with the tree bark. Normally, fence wires, or similar, such as something to hold a hammock, will go unnoticed by the tree.