if it bleeds, it has veins. if it has veins, it has a vein system. if it has a vein system, it must have something to pump the blood through the body. that means a heart. if it's mechanical or biological or biomechanical, it is, in the very essense, what is a heart. damage/destroy the heart, end of story.
funny enough, i have not seen a mention of that ever. it must have a heart, there is no way around it. even if it has acid for blood, the acid is part of the blood, and more of a protective feat than anything. the blood must carry oxygen or other nutrients for it to be able to function and live.
even if it is a perfect organism, it's still an organism. that means it has a biological build that demands certain organs. brains, a heart, blood, longues, probably liver, bowels, a stomach, etc. it definately has various glands. it produces saliva, so it needs glands for that. it also is able somehow to secrete resin, as it builds a nest/hive. it somehow thus must be able to secrete resin. it needs a gland for that too.
in any case, it's a living organism, that serves a function, and is more or less a biomechanical machine with a goal. its offcourse very interesting all that, but it only means that it is something that is lives, and something that lives, is able to die.
a rock is lifeless, end of story. a robot is not a living organism, but even then it can be terminated.
if the alien couldn't die, it wouldnt need acid for blood. if it was invincible/indestructable, it would not 'tacticaly' move but simply go from human to human and kill them one at a time.
it's as both lethal as it is mortal.
i like the fact the ship simply had no guns. we also saw that is sufficiently strong that when a human tried to attack it with an axe or whatever it was (when lambert was about to be lobotomized) that it defended itself from the attack. the only thing the crew had was the flamethrower.
also, we saw that steam or perhaps cold air also hurts it. it thus is able to sense pain. for example, when ripley wanted to blow it out of the airlock in the narcissus, she did something that saw some steam sprayed on it, and it screamed as it did hurt it. and it got rather pissed off by it too.
it has thus emotions, it has feelings. Ash stated it was not hampered by moral codes, when he paired it to say it was the perfect organism.
apart from the moral aspect, it is just as mortal as the rest of us. Dwayne Johnson is stronger than me, but he's just as mortal.
if a soldier wears a bulletproof vest, he's still just as mortal.
'a tough 'sonofabish'' but never undestructable.
guns kills it, there simply weren't aboard. and even if they did, one must question, would it be wise to shoot at the creature and either
a) shoot a hole in the hull with devastating results
b) shoot a hole in the creature and have its acidic blood burn a hole in the hull with devastiting results.
'you have my deepest sympathy'
indeed, even if the crew had guns, they didnt stand much of a chance, perhaps even less.
they wanted to shoot it out of the airlocks, that was the only solution. not neccesarily to kill it,
but it wouldnt be able to do anything to them anymore.
even if it's body could withstand the pressure, it would die from radiation, cold, and lack of ingredients for sustaining life.
a human in an astronaut suit can stay outside of a station for a while, but if it was disconnected and drifting in space,
it would die eventually. soon enough from oxygen, really, but it wouldnt explode or decompose in seconds in space.
as for the engine thing,
it was clear to me that it got hurt from the engine blow. the engine was not on when it grabbed onto it, it was however
rather hurt by it, showing it got damaged. you hear it scream, it cant hold on to the engine obviously, and you see imho
fragments of burnt alien spraying around. tiny, but i thought i rememberd seeing 'something like a cloud' / steam coming
off the alien.
it is to all its core, mortal.
