There are secret pets that aren't listed in the egg preview. This guide reveals how to unlock them.
Hatch 100 Cracked Eggs in a row without leaving the nursery. After the 100th hatch, you'll get a Golden Unicorn egg.
At midnight (in-game), go to the graveyard behind the school. Click the glowing tombstone. Complete the maze within 60 seconds.
Trade 3 legendary pets to the secret trader who appears in the beach cave every Sunday between 2-3 PM GMT.
During Halloween event only: collect 500 candy corn, then feed 100 candy corn to the elephant statue in the event area.