Facility
Worker producer/upgrader
Used for creating new workers of your color and upgrading them.
The upgrades of this facility specifies the properties of workers at a certain level. For example the workers of level 3 benefits from the facility's upgrades at level 2 and 3, and the workers of level 5 benefits from the facility's upgrade at level 2, 3, 4 and 5.
When you produce a worker you have to wait some time before you can produce antoher one or spend crystals to produce more workers on the same recharge cycle.
The level of newly created workers are in the range of 1 to the level of this facility. Most likely the lower lewels.