This is the crosscut bottom view of this cool encased insulator. You can see the original nail sticking thru the back. You can also see the original bark still trapped underneath the sidepin when it was grown around. This tree must have grown really fast to engulf this rather than force it off. I nailed a sidepin on a tree 14 years ago and watched to see what it would do. After about 6 years the pin was finally forcibly removed by the growth of the tree thus indicating that the slower growth rate created enough pressure to break and slough the pin off before the tree had a chance to grow around the pin.