How to spot an alien

Close Encounters of the Third Kind (1977) Photograph: Ronald Grant Archive

Original illustration from H G Wells' The War Between the Worlds. Simon Conway Morris from Cambridge University believes aliens will share our tendency for greed, violence and exploiting others' resources
Photograph: Corbis

They may discover that our warm, moist bodies make ideal incubators ...
Photograph: PR

... So that when their offspring emerge they're ready to hit the ground running. Alien: The Director's Cut (2003)
Photograph: PR

The artist H. R. Giger sculpted the adult aliens from plasticine, incorporating terrestrial body parts such as snake vertebrae and cooling tubes from a Rolls-Royce
Photograph: Allstar/Cinetext/20TH CENTURY FO/Sportsphoto Ltd/Allstar

If you thought Ridley Scott's alien was over the top, think again. This is an amphipod phronema sticking its head out of its house, the hollowed-out living body of a salp where it will eventually lay its eggs and raise its family
Photograph: Russ Hopcroft/University of Alaska Fairbanks

My Little Alien by artist Mari Kasurinen
Photograph: Public Domain

In 1999, a toy designed to resemble an alien baby closed down a London Underground station after it was mistaken for a human foetus. Police and paramedics rushed to Buckhurst Hill in Essex after a supervisor found the small rubber figure coated in clear sticky goo on a darkened platform
Photograph: Phil Noble/PA

Archetypal alien: Alien Autopsy (2006)
Photograph: Warner Bros

In 2006, the Guardian reported that screenwriter Barney Broom had discovered a baby alien in his attic, 'stored in an old toffee jar wrapped in a copy of the Daily Mirror dating from October 1947'
Photograph: Graham Turner/Guardian

A still from the film Alien v Predator (2004). Note the body armour decorated with the remains of some of this predator's terrifying adversaries
Photograph: Public Domain

A depiction of an alien from more innocent times. E.T. The Extra-Terrestrial (1982)
Photograph: Allstar/UNIVERSAL/Sportsphoto Ltd./Allstar

Leonard Nimoy as Mr Spock in Star Trek: The Wrath of Khan (1982). Vulcans are technically aliens, though the only features distinguishing them from Homo sapiens appear to be plucked eyebrows and pointy ears. Special powers: Vulcan death grip and mind meld
Photograph: Sportsphoto Ltd/Allstar

Former Conservative cabinet minister John Redwood is not technically an alien but has been (unkindly) compared to a vulcan. Special powers: none
Photograph: Dan Chung/Guardian

Never trust an alien. Mars Attacks! (1996)
Photograph: PR

President George Bush as satirised by Guardian cartoonist Steve Bell in 2003
Photograph: Steve Bell/Guardian

So long and thanks for sharing your natural resources with us
Photograph: Colin Anderson/Blend Images