Barnacle

A barnacle eating the legs of a Fast Zombie.

Barnacles are Xen wildlife seen in all Half-Life games to date. Their basic characteristics are their brown (red in Half-Life and its expansions) hue and long tongue. Barnacles will attempt to eat everything that touches their tongue, that appears to be sticky, and chew at it - if the object is edible, that is, alive, the Barnacle will devour it and eat the body completely. If the object is dead or inanimate the barnacle spits it out, often to pick it up and taste it again.

Appearances

Barnacles are first seen in Half-Life, right before the Office Complex chapter. A Bullsquid seen in this scene does not attack them. They return in most chapters of the game. In Blue Shift and Opposing Force they also appear (and have a extended role in the latter, see below). They are encountered in Half-Life 2 and both of the episodes.

Barnacle Gun

In the Half-Life expansion Opposing Force, Adrian Shephard, the player character, aquires a detached Barnacle for use as a weapon. It is used as a grapple hook and a means for drawing enemies closer to the player. The final battle against the Gene Worm requires use of the Barnacle Gun to win.