From Star Wars Combine :: Game Guide
As of Year 13 Day 228 (July 15th, 2012), wild creatures, when killed, have a very slim chance of dropping mysterious eggs. These eggs behave like normal trophy items and can be claimed by players however they have a secondary and far more valuable purpose. Their content is unknown and all look identical. It is therefore entirely possible for an egg to contain a simple Eye-snatcher, Bantha or even a Rancor. Players may be able to customise the eggs through the use of Combine Points however since the item is expendible and the design in no way affects the outcome, this may be unwise.
Uses of Eggs
Eggs can be incubated and eventually hatched. It is speculated that this may be designed so that a player may breed a creature for domestication and add to their party or for possible collection purposes. In order to hatch an egg, the player must find an incubator.
These devices are located in the control room of all Ranches, Zoos and Wildlife preserves. The egg may be added to the incubator and then after a period of time, the egg may hatch into a random creature.