The world egg, cosmic egg or mundane egg is a mythological motif found in the cosmogonies of many cultures that is present in Proto-Indo-European culture and other cultures and civilizations. Typically, the world egg is a beginning of some sort, and the universe or some primordial being comes into existence by "hatching" from the egg, sometimes lain on the primordial waters of the Earth.

Eggs symbolize the unification of two complementary principles (represented by the egg white and the yolk) from which life or existence, in its most fundamental philosophical sense, emerges.