This is a harness anchor attached near the apex of the roof. This addition makes navigating the roof much safer should the person have proper harness and repelling gear. I even inspected the fasteners (nails) to make sure they wouldn’t offer a roof leak, and, as you can see, the nails are equip with rubber gaskets to discourage water infiltration even though they are inserted through the roof covering itself.
This house was newer, and from the rooftop i could see that the builder of this development added this anchor as a standard on all of the houses he or she built. Well Done!