Egg

Eggs were a method of reproduction where the offspring developed outside the body.

The air of Belepheron reportedly smelled like bad eggs. (NSA: The Last Dodo)

Egg-laying Species
A wide variety of creatures laid eggs, including fish, amphibians, reptiles, birds, monotremes, arachnids and insects. Some specific species include:
 * Aubertide (NA: Human Nature)
 * Bane (SJA: The Lost Boy)
 * Centuripede (K9TV: The Last Oak Tree)
 * Chelonians (MA: The Highest Science)
 * Chimeron (DW: Delta and the Bannermen)
 * Earth Reptiles
 * Gappa (NSA: Snowglobe 7)
 * Gastropod (DW: The Twin Dilemma)
 * Ice Warrior (NA: Lucifer Rising)
 * Krill (PDA: Storm Harvest)
 * Mayflies (TW: Reset)
 * Nostrovite (TW: Something Borrowed)
 * Racnoss (DW: The Runaway Bride)
 * Raxacoricofallapatorians (DW: Boom Town)
 * Saraani (BNA: Dry Pilgrimage)
 * Viperox (DW: Dreamland)
 * Wirrn (DW: The Ark in Space)

Food Source
Eggs were also prepared and eaten as food. On Earth, chicken eggs were eaten.

Barbara Wright ate a foodstuff, processed by the First Doctor's food machine, to taste like bacon and eggs with brown sauce. (ST: 1963)

Sarah Jane Smith tried and failed to make scrambled eggs on several occasions. When she tried to make some before Luke Smith went to University, she accidentally set her kitchen on fire. (SJA: The Nightmare Man)