Sometimes when a player loots living chests they will find Mystery Eggs. These are essentially a type of a mystery box but for spawn eggs. When holding a Mystery egg and right clicking, a random passive spawn egg will drop.
Mystery eggs can also be crafted to a Hostile Mystery Egg, which function the same but will drop hostile eggs instead.
The main usage of these spawn eggs are in the mods Cagerium and Ispawners. In these mods spawn eggs can be used to obtain the spawn egg's mob drops. For example, having a pig egg with either of these mods will let you get infinite porkchops.
Mystery eggs can also be obtained from Bounties, Black Market, Flesh Chests and Resource Cards.
The drop chances and the available eggs are:
| Icon | Name | Chance |
| (Icon will be needed for the eggs) | Pig Spawn Egg | 16.89% |
| Sheep Spawn Egg | 13.51% | |
| Chicken Spawn Egg | 10.81% | |
| Cow Spawn Egg | 10.81% | |
| Cod Spawn Egg | 4.05% | |
| Mooshroom Spawn Egg | 2.70% | |
| Rabbit Spawn Egg | 2.70% | |
| Salmon Spawn Egg | 2.70% | |
| Squid Spawn Egg | 2.70% | |
| Bee Spawn Egg | 2.02% | |
| Cat Spawn Egg | 1.68% | |
| Goat Spawn Egg | 1.68% | |
| Tropical Fish Spawn Egg | 1.68% | |
| Dolphin Spawn Egg | 1.68% | |
| Polar Bear Spawn Egg | 1.36% | |
| Bat Spawn Egg | 1.36% | |
| Parrot Spawn Egg | 1.36% | |
| Pufferfish Spawn Egg | 1.36% | |
| Donkey Spawn Egg | 1.36% | |
| Axolotl Spawn Egg | 0.67% | |
| Glow Squid Spawn Egg | 0.67% | |
| Panda Spawn Egg | 0.67% | |
| Strider Spawn Egg? | 0.67% | |
| Turtle Spawn Egg | 0.67% |