|Cork. Nikon D7000
Cork is a wonderful natural product. Although it is tree bark from the cork oak, it is still used for making stoppers for many types of bottles.
Its use is being replaced slowly by screw caps and plastic stoppers, but for the special cases of 'fizzy white wine', proper corks still seem to be the chosen bottle sealant.
Popping the cork on a Champagne bottle will always sound different to releasing the fizz by unscrewing a cap.