Onion-skin: Light weight cockle finish "bank paper" often used for airmail stationery.

slide - "as we go to higher and higher energies smaller and smaller distances, the next onion skin manifestation of the basic law resembles the previous one to some extent."

The structure of an onion allows us to perform the skin-peeling exercise several times, progressing ever deeper into the onion’s inner secrets with every skin peeled off.