Clickling

 One of the most annoying enemies in NOTD. The Clickling is much like the Baneling, except its bigger, hits harder, and is designed to waste ammunition. However the Clickling can be killed in a unique manner, like its namesake, a Clickling can be killed by clicking on it. It takes exactly 5 mouse clicks to kill a Clickling. However, lag and hitbox issues often result in this appearing to be much greater amount.

The clickling is a baneling that has survived past the usual lifespan of a baneling (1 - 2 weeks) due to a mutation that strengthens the acid containment membranes that banelings possess. Due to the new membrane, clicklings have adopted a psionic trigger to explode rather than a physical one and therefore explode when near a foreign psionic being (such as a marine). Due to the membrane, clicklings are very hard to kill with conventional marine weaponry but the triggering method means that marines can easily kill a clickling by focusing their limited psionic capabilities against it.

Psionic Sensitivity
A Clickling can be killed easily through the application of psionic force (aka, clicking it five times). Despite this weakness, clicklings are often more dangerous than banelings as they can easily catch a Marine unaware, hit harder, and are nearly impossible to kill through conventional methods before exploding.