Artistic styles

Artistic styles change over time and throughout cultures, yet some forms continue to be repeated despite the changes. Examining these forms helps in finding the meaning.
View the three works of art from the hyperlinks below. They are all from different time periods and cultures. Notice how each one has a repeated formal element similar to the others.
What style and category does each work belong to?
Do these similarities have ties to a common meaning between all of them, or do you think the meaning for each work is separate from the others? Why or why not?
What cultural, religious or other considerations do you take into account in defining your answers?
Here are the images to view: Totem Pole Giotto Crucifix Minoan Snake Goddess