Eternal Realms implemented a feature since the launch of the Public Beta that allows you turn any passive mob back into its spawn egg. These eggs can be stored just about anywhere and can be used at a whim.
Eggifying any passive entity costs 50 ether per use.
All animals will become babies when eggified.
Horses, Llamas and Pigs do not keep any items they have equipped when eggify. In fact, any entities with inventories will drop their inventories to the player when eggified. Use the Stables feature to maintain ownership and growth.
Only passive mobs with spawn eggs are currently supported.
To turn a entity back into its egg, you right click it with a stick. It will disappear and an egg will appear in your inventory. Your account will automatically charged.
[Note] You must have an open inventory slot as well as the required amount of Ether to proceed.
Cats, parrots, rabbits, foxes and mooshrooms will not save their color variant when you eggify them. This is useful when you want to change the color or style of an animal.
Sheep will maintain their wool color when eggified.
Eggified horses will maintain their stats (speed, health and jump) when eggified and spawned.
You use the egg like any other item. Hold it in your hand, and right click the egg on any block to spawn it.