?->Big_Bang->Energy/Light/Gravity<->Elementary_Particles->Supernovae<->Stardust (carbon, iron, silicates etc)->Organic_Chemistry (amino acids etc)->DNA<->RNA->Protein (enzymes etc)<->Cell/Protista->Egg+Sperm<->Multicellular_Organisms (chicks et al.)

There are feed back loops in this chain (web, actually) but from an evolutionary 'historic' perspective the 'egg' (and sperm) preceded the cellular aggregates that evolved as organisms to utilize the egg/sperm as their mechanism for sexual reproduction. Examples are plenty, for instance in planctonic algae.

allan