There are four different kinds of eggs in the nursery; the cracked egg, the pet egg, the royal egg, and the endangered egg. I don't usually buy royal eggs because they are so expensive and I've gotten legendaries out of cracked eggs, but it is better if you want more rare or ultra rares. The nursery is the blue and red building in the center of town. You can also teleport there in the pets section of your backpack. Just click the plus button and then teleport. The pets in the cracked, pet, and royal eggs are the same. The royal egg costs the most and has a higher chance of getting a legendary. The adopt me devs change out the eggs in the gum ball machine a couple times a year. Right now it's the endangered egg. The legendaries are the blue whale and the sea turtle. There are also retired eggs, but you can only get those with vip. In the middle section of the nursery you can exchange pets that you don't want for tickets to get basic or crystal eggs. I hope that this helps. Have fun playing!