Nydus worm

The nydus worm is a zerg transport strain. Each Nydus Worm acts as an opening in a system of tunnels created by the Nydus Worm.

Balance issues are surrounding the Nydus Worm at this point in time, given the rate at which Nydus Worms can unload units in enemy bases. It may be cut from the game.

At the World Wide Invitational 2008 art panel, it was stated that "there is no worm" and it functions like a stationary canal.

Game Unit
The Nydus Worm is built from the overseer. It no longer needs creep to spawn.

It has a short "build time" (5 seconds) after which it bursts out of the ground. It cannot "rebury" or move in this state.

The Nydus Worm can be used to transport as many units as are selectable (up to 255 in the current build). However, only the first 12 units inside can be seen. It cannot transport Zerg defensive structures. The units are transported to a fixed location. Units can move back and forth through the system. Units can enter the network through a Nydus Network. The Nydus Network doesn't have to be the "first" entrance.

If a Nydus Worm is destroyed, the units that are loaded in the network will not be destroyed as long as there are still Worms or a Nydus Network in the system. If all the Nydus Worms are killed, then all units being transported will be destroyed.

Strategies
Nydus Worms can quickly transport units between multiple Zerg bases, in a manner similar to Nydus Canals.

Using multiple Nydus Worms to transport units into an enemy base quickly is suggested, as Nydus Worms can be quickly killed due to their low hit points.

Nydus Worms are an expensive way to "drop" units into an enemy base, and are a bit more difficult to use than other transport mechanisms because it requires Creep. However, Overlords can be used to drop Creep near enemy bases.

A Zerg player can unleash Nydus Worms near multiple enemy bases, then choose to send Zerg only against the base the enemy does not reinforce (in effect, tricking their opponent).

A Zerg player loads their units into a Nydus Network and unloads them at the same Nydus Network or at any Nydus Worm they have built. You can use the Worm to quickly move some drones over to a newly built expansion. You could use one to expand on an isolated island by creating Creep there with an Overlord. You could store your Morphalisks in the Nydus Network to keep them safe. It may also prove useful to build the Nydus Network close to your Drones, in case of enemy raids.

Development
In June 2008, the nydus worm was built directly from the Nydus Network, a point on the Creep is selected (it can only emerge onto the Creep) and the Nydus Worm erupts.

The Nydus Worm used to be a mobile worm unit with two modes, "stationary" and "mobile". There was a delay when it shifted from one mode to another.

The Nydus Worm was visible without a detector while transporting units underground and is capable of traversing gaps between space platforms.

It has since become a stationary structure.