We know the tube drills & how to make them.. but stones 🪨 all over the world had nubs too.

Wide range of theories on these

One theory

"The enigmatic nubs left on otherwise finished stones is not for lifting, or because the stone workers got lazy. They are positioned around gates, doorways and passageways to deflect discharges away from where people walked.

An energized stone, especially one being struck by lightning, will absorb and discharge current, and one doesn’t want that to happen across the doorway you are walking through. So the nubs are collector points for charge to accumulate and discharge safely, and help desaturate the stone near the seams, openings and walkways they are placed around."