If I could, I'd make an animation about what I saw. I never played metroid, so here goes a small description...
I started to descend into a huge hole, grappling my way into a smokey nothingness. As soon as I landed, I pulled out my plasma rifle (I just pictured the doom marines wep) and swept around my area of view from where I kneeled. I call to my partner to say that it was clear and we can continue. Then I heard a grunt, and down fell my partner. He fell horizontally without banging into anything, and went splat. He was pushed by a bizarre being at the top of the hole. Then, creatures I didn't see before opened up their fire on me. The noise must have given me away. "Damn it, here I go again..." That's just a tiny bit.