This was only a beta feature that was wrongfully added for everyone in 3.12.1. It was removed, but then later re-added in Version 3.20.0. It seemed that the feature was not available to all players in later versions, and it seemed random as to which players had the feature or not.
An announcement was made on 28th November 2019 that the Royal Egg Bank was being disabled. It seemed to be operational for some for another week or so, then as of the Version 4.5.0 update it has disappeared.
The Royal Egg Bank, featuring Kala, is a chance to obtain special/Events eggs at a small price of 5 Dragon Gems (the newer version has different gem prices). It is currently not known whether different gem prices are linked to different features such as more available choices at higher costs.
Jeweled Eggs (colored green) might be obtained when retrieving your daily treasure chest, which gives 0-3 of these eggs alongside. Also, when collecting the reward from Kala's daily trade quest, the bonus sack (if given) might also become 1 jeweled egg. Tapping a Jeweled Egg will fill up a bank slot as well as providing you with a free magic coin gold or Spellium. In the Bank menu, tapping a green egg will either yield a random trophy dragon egg or a special choice egg (colored red as seen in the images). The special choice eggs can be further tapped to reveal 3 random trophy dragon eggs from which you can choose 1. The choices available can be reset by exiting and re-entering the game. When the bank is filled up, a mystery item is included. Jeweled Eggs may still be received even when your bank is full, and in this case tapping one will only give 5 coins directly to your stash and the egg will be gone.
Possible Mystery Item Bonuses
| Item | Level | Quantity | Notes |
|---|---|---|---|
| Trophy Dragon | 1 | 2 or 3 | Aqua, Cat, Cool, Diva, Dog, Ghastly, Martian, Moon, Morpho, Onesie, Passion, Sea, Winter, and Wood Dragons have been observed. Others may be possible as well |
| Trophy Dragon | 2 | 1 | See above for possibilities |
| Fountain of Legend | 1 | 2, 3, or 4 | |
| Midas Tree | 4 | 1 | |
| Mystery Nest - Supernest | n/a | 1 | |
| Life Tree Sprout | 8 | 1 | |
| Giant Life Flower | 7 | 4 | |
| Brilliant Life Flower | 6 | 8 | |
| Nest of Midas Eggs | n/a | 1 | Contains 3-7 eggs |
| Nest of Pegasus Eggs | n/a | 1 | Contains 3-7 eggs |
| Small Zen Temple | 1 | 1 | |
| Kattryx Monster Idol | 1 | 8 | |
| The Gromblin Mythical Idol | 1 | 2-3 |