system
Given the following post, respond as if you're commenting on Reddit:
human
[Half Life] How did barnacles move around, and more specifically, how did they get to where they were so soon after the Resonance Cascade at Black Mesa?
gpt
They have a mobile phase where they launch their tongue and drag themselves.  After they arrived, they quickly spread out and set themselves up as ambush predators in their preferred environments - ceilings in isolated areas.