What tree is this, and why does it seem to be looking at you?
This is a branch scar on an Aspen tree. Aspen trees self-prune lower branches, cutting off the flow of sap to let them die. These lower branches would be shaded by upper branches, so their leaves would not get enough sunlight, so the tree gets rid of them to be more energy efficient. You can often see a small, similar scar where leaves were attached to branches.