In the Byzantine era artists created halos on Saints to move like a plate affixed to the plane of the art. Then, with more sophistication, like a hat. Hats move with the head.
Italy. Santa Croce. Giotto. Does a halo move like a hat?

In the Byzantine era artists created halos on Saints to move like a plate affixed to the plane of the art. Then, with more sophistication, like a hat. Hats move with the head.