A 36mm-diameter, 1mm cross-section Latex ring floats on the surface of the water in a funnel. The water is slowly removed, the surface area decreases and the ring is compressed and buckles into a 'yin yang' shape.
A rubber ring passes through a funnel

A 36mm-diameter, 1mm cross-section Latex ring floats on the surface of the water in a funnel. The water is slowly removed, the surface area decreases and the ring is compressed and buckles into a 'yin yang' shape.

https://fluids.ac.uk/files/09_Photo.1512131242.jpg