What would an alien look like

[wolram]

Assume it could be from a world where the gravity is much higher or much lower than ours,
it could be much hotter or colder than ours, it would have to have a method of manipulating tools.

[Ryan_m_b]

Similar to pretty much anything from this (http://4.bp.blogspot.com/-YkVhy6KWXfU/TbxSNBeu0jI/AAAAAAAApYE/edYA02hHg_s/s640/Strange_Animal_alien.JPG) to this (http://www.notsoboringlife.com/wp-content/uploads/2007/04/roundworms.jpg) or maybe this (http://genesispanthesis.tripod.com/fossils/tetraceratops.gif) or perhaps even this (http://www.cthulhu.org/cimages/cthulhu_caves.gif). Semi-sarcastic point being that there is huge variety in how life can evolve on a single planet, there is little in common beyond biochemistry and development (and those are potentially just artefacts of chance). I don't imagine that anywhere else in the universe with life would be different.

However in the spirit of the question...
Assume it could be from a world where the gravity is much higher
Creatures would be low lying with perhaps a tendency for cushioning, sea life is less affected and simply adapts to conditions of higher pressure. If the atmosphere is significantly higher pressure far larger flying creatures could evolve.
Or much lower than ours,
Heavy animals may evolve to avoid predators, flying creatures would need huge wings and high metabolism to fly in the low pressure atmosphere.
it could be much hotter
Life adapts to low moisture conditions, tendancy for basking. Plants are few and far between.
or colder than ours
Combination of slow growing slow metabolises and fast growing predators.
it would have to have a method of manipulating tools.
Anything with a hand, claw, mouth, tentacle, tail....

[wuliheron]

Knowing my luck they'd all look like my mother-in-law.

[Office_Shredder]

Actually I kind of like the idea of a movie where aliens come earth and find they can't fly because our atmosphere is much thinner. You could see them jumping from their spaceships hovering over all our major cities as part of a coordinated major attack and just falling to the earth and going SPLAT

[wolram]

Actually I kind of like the idea of a movie where aliens come earth and find they can't fly because our atmosphere is much thinner. You could see them jumping from their spaceships hovering over all our major cities as part of a coordinated major attack and just falling to the earth and going SPLAT

I too have thought of this, low gravity beings would have no chance.

[Ryan_m_b]

Actually I kind of like the idea of a movie where aliens come earth and find they can't fly because our atmosphere is much thinner. You could see them jumping from their spaceships hovering over all our major cities as part of a coordinated major attack and just falling to the earth and going SPLAT
I know your joking but this is the exactly type of bizarre illogical plot that is pervasive in Tv and film SF; a super advanced alien race travels lightyears to Earth in interstellar vehicles only to suffer engine failure over Nevada or die because they're allergic to water (and didn't realise the planet they were visiting is covered in it) or some equally banal catastrophe that's intellectually equivalent to an Antarctic exhibition of today forgetting clothes.

[gneill]

I know your joking but this is the exactly type of bizarre illogical plot that is pervasive in Tv and film SF; a super advanced alien race travels lightyears to Earth in interstellar vehicles only to suffer engine failure over Nevada or die because they're allergic to water (and didn't realise the planet they were visiting is covered in it) or some equally banal catastrophe that's intellectually equivalent to an Antarctic exhibition of today forgetting clothes.

I would like to see that exhibition.

[Ryan_m_b]

I would like to see that exhibition.
Oops, iPhone autocorrect lol

[QuarkCharmer]

Isn't it obvious?
http://arcturi.com/sitebuilder/images/Ancient_Airplane_Model-75x90.jpg
http://troll.me/images/ancient-aliens-guy/the-pin-i-wear-on-my-jacket-is-an-ancient-alien-airplane.jpg

[Drakkith]

I know your joking but this is the exactly type of bizarre illogical plot that is pervasive in Tv and film SF; a super advanced alien race travels lightyears to Earth in interstellar vehicles only to suffer engine failure over Nevada or die because they're allergic to water (and didn't realise the planet they were visiting is covered in it) or some equally banal catastrophe that's intellectually equivalent to an Antarctic exhibition of today forgetting clothes.

Reminds me of the aliens in Battle Los Angeles that have ONE drone controller that is taken out by ONE missile that renders their drones completely inop. TERRIBLE plan.

[gmax137]

I kind of like the idea (following Lovecraft?) that the aliens emotions and motivations are completely incomprehensible to us.