Lair

The lair is the second major step in the evolution of zerg breeds, providing increased toughness and extended access to the stored genetic knowledge of the Overmind than the hatchery. The lair is responsible for producing larvae, maintains the creep, digesting minerals\gas, and mutating the Burrow upgrade.

A lair can be mutated into a hive.

The Lair in StarCraft II
The lair reappears in StarCraft II. The lair can set two rally points, one for most units and one for drones.

Each individual egg can be separately rallied; this overrides rally points set for the lair.

Upgrades
The lair researches a speed upgrade for overseers as well.