Drone

The Drone is the Zerg worker unit.

Overview
Drones stem from the savage Gashyrr Wasps of Eldersthine, absorbed into the Zerg Swarm to serve as resource gatherers. Over time they became Drones, engineered with the Larvae's ability to break down their own genetic coding and transform themselves into rudimentary Zerg structures. A transforming Drone needs Creep to provide nourishment and mass to support its new form.

Like the Larva, Drones are controlled by Overlords who monitor their progress. Not that they require much maintenance however, as Drones are unusually single-minded about their tasks, diligently working through even raging combat.

Drones posess limited combat ability, but in a swarm, they can present a significant threat, attacking with claws and spines.

StarCraft
Drones 'transform' into the buildings they construct. The only way to stop a building from completing is to destroy it or to cancel it, after which the Drone is recovered and maybe used for some other purpose. Once the building is complete the Drone is permanently lost.

Drones benefit from burrow. Unless the enemy brings detectors burrowing can minimize the damage caused by a raid on harvesting operations. Once the enemy is repelled harvesting may immediately resume without requiring the replacement of all workers.

Upgrades

 * Carapace
 * Burrow