When you feed your pets, they will produce a chest of goodies that varies in value. The most rewarding chest is gold, then silver, iron, and lastly, wood. Crystal blue chests are produced by exclusive pets available at level 69.
The chances of obtaining a specific chest vary per pet. For instance, when you feed the Egghead Owl, you have a 55% chance of getting an iron chest, 40% silver, 5% gold, and no chance of getting a wood chest. Before you work to obtain pets, it’s important to know how well they will reward you when you feed them.
Once you have the pet, you can verify the percentages by tapping on them, but this is a convenient at-a-glance reference. Every pet is listed in alphabetical order with the chances for getting each type of chest.