The surface of revolution of a
superellipse given by the formula |x/a|2.5
+ |y/b|2.5 = 1, where a/b = 4/3.
The superegg was named by Piet Hein and singled
out by him because of an unusual property: stood on either end it has a
peculiar and surprising stability. Supereggs, made of metal, wood, and other
materials, were sold as novelties in the 1960s; small, solid-steel ones
were marketed as an "executive toy." The world's largest superegg, made
of steel and aluminum and weighing one ton, was placed outside Kelvin Hall
in Glasgow in 1971 to honor Hein's appearance there as a speaker.