Egg balancing, a Chinese tradition

Gömböc, an egg-like (convex, homogeneous, solid) 3-D body that has only one stable equilibrium

Gordian Knot, a legendary impossible knot

Hindsight bias, the inclination to see events that have already occurred as being more predictable than they were before they took place

Superegg, an egg-like shape designed by Piet Hein that stands on its ends

Väinämöinen in Kalevala was asked to tie an egg into a knot, in which he succeeded

image Egg of Columbus

define Egg of Columbus

wikipedia Egg of Columbus

weblio Egg of Columbus

kotobank Egg of Columbus

jisho Egg of Columbus