What is a symbol for protection?

There are a large number of symbols used for various kinds of protection.

One of the easiest to draw is three interlocking circles.

Slightly more difficult is the Dragon's Eye. An equal-sided triangle, with additional lines running from each point to the centre of the figure. A Neo-Pagan symbol of protection.

The one I find the most difficult to draw is the Penelope's Web

• a neo-Pagan symbol of ten interconnected stars, used for general

protection and to ward against negativity.