What starts everything?

I thought the same thing, and once the atmosphere there was tainted, all hell broke loose! The viles of goo just kept flowing out, exaclty like a nest. Life expanding from a very central point, around a large Human Head.... I need to see this movie again tomorrow now.... Lol

Well I agree. This could be kind of security system of ampule vessels - they are safe and solid until a life-form comes closer.

What happened was..... That room with the ampules was sealed. Sealed so well that the engineer's head was perfectly preserved for 2000 (+ or -) years. This means that the ampule room was hermetically sealed. When David opened the door it was like exposing everything in a sealed tomb to oxygen. In the absence of oxygen, things stay preserved. [u][i][b]Oxygen[/b][/i][/u] is what caused the goo to start flowing. Oxygen is what caused the wormy things to wake up. Goo + wormy things = hammerpedes....the things that killed all those engineers 2000 ( + or - ) years ago and left them in a pile with some climbing to what may have been the lock on the door.

Were the worms brought in through their boots, or already there..? I haven't seen the movie, so the worms were like frozen, and came back to life or what..?

Or! Interesting theory, what if this "black goo" was solely intended for humans and humans alone, as in to react to their presence, hence why it didn't react to David, whatsoever.....

Sorry this took long for me to get back to, but oxygen was already present. What wasn't present was the carbon dioxide. You see, when you're watching the scene, you don't see the air rush in, and yes I said "see" because when the door lifts up there is already some sort of fog in the room and everything stayed the same when the door opened up.....When they got closer to the ampules, reactions started occurring, and quite rapidly.....