The eggs were special cargo when Dr. Barlow boarded the Leviathan. They eventually hatched into perspicacious lorises. The eggs were supposed to be taken to the Ottoman Empire, where one of them could be a gift to the sultan.

Dr. Barlow brings the eggs on board with her when the Leviathan lands in Regent's Park. The eggs are kept in the machine room of the Leviathan. Many of the eggs are crushed when the Leviathan crashes in the Swiss Alps. Four of the eggs survive the crash. Dr. Barlow keeps the eggs heated with a bacterial warmer. Deryn, Newkirk, and Alek are responsible for keeping the eggs at the correct temperature. Newkirk destroys one of the eggs when he is confused by the Clanker Celcius system and overheats the machine room. One of the eggs, Bovril, hatches for Alek before he escapes to Istanbul. Dr. Barlow offers one of the eggs to the Sultan, whose automaton crushes it. The remaining egg hatches for Dr. Barlow and becomes her loris.