By Stephen Dowling
BBC News Online entertainment staff
The gruesome alien "chest-burster" - an embryonic monster that emerges in bloody style from John Hurt's chest in Ridley Scott's 1979 sci-fi classic Alien, was among items up for auction in London on Tuesday.
The alien, which was eventually purchased by singer Chris de Burgh for just under £29,875, took pride of place among film and pop memorabilia items on show in Bonhams' auction rooms.
The 1979 Alien model - a flexible metal creation powered by hydraulics - was built by special effects master Roger Dicken, who decided to sell it 25 years after the monster defined one of cinema's most terrifying moments.
Also in the sale was the Imperial Shuttle from Star Wars film Return of the Jedi. It may have been seen for only a few seconds on film, but the detail is painstaking.
Such items are far removed from the rarefied domain of fine art, however.
Stephen Maycock, Bonhams' entertainment specialist, has been involved with music and film memorabilia in the UK since the first rock auction, by Sotheby's, in 1981.
A John Lennon photo by actor Leo McKern is included in the sale
Before the first Sotheby's sale, he said, rock and pop memorabilia had been a hit-and-miss affair, with aficionados having to trawl magazines or set up private swaps to acquire iconic heirlooms.
Mr Maycock said a piece such as the "chest-bursting" alien comes up "very rarely".
"This is a really iconic piece, not only does it represent one of the most shocking moments in modern cinema, but it's a dying art. It's the craft of the technician," he said.
A prop Gatling gun from the James Bond film Die Another Day - £500-£600
A signed publicity photo of the Beatles in their Hamburg era - £3,000-£3,500
A Fender Squier Telecaster guitar signed by Oasis' Noel Gallagher - £300-£400
A letter from Richard Burton to wife Elizabeth Taylor, saying he was tired of being an actor - £500-£700
Return of the Jedi scale model of an Imperial landing platform - £2,500-3,000
Compared with the computer-created special effects of today, the movie-makers of a quarter-of-a-century ago had to "conceive the monster and then build it", he added.
Bonhams' auction showroom also displays giant posters advertising Madonna concerts in France as well as models of wrecked landrovers used in the recent fantasy film, Reign of Fire.
Kristianna Loken's figure-hugging leather outfit from Terminator 3: Rise of the Machines is arranged on the wall, opposite giant photographs of Rolling Stone Keith Richards and David Bowie from the early 1980s.
Mr Maycock still remembers Sotheby's first pop memorabilia sale, saying: "It attracted a huge amount of media and public interest, but there was also a lot of scepticism.
"The amounts seem very modest now, but you have to remember that this was 23 years ago, and people were prepared to pay hundreds of pounds for a Beatles autograph.
"Now people will pay six-figure sums for something to do with John Lennon."
The most outlandish piece of Beatles memorabilia he has witnessed at auction was a bath thrown out of John Lennon's Ascot home.
"I put it in a sale just to see if it would sell," he says. "And it sold. For about £800, I think."
Despite cinema having a more extensive history than pop music, the film memorabilia market took a lot longer to become established.
Alongside 50s matinee idol posters and photographs, one of the most collectable areas has been the props, costumes and model monsters from modern movie-making's blockbuster phase.
But Mr Maycock was quick to point out that few props from more modern films up for sale, aside from the Reign of Fire models and costumes from the latest Terminator film.
He said it is unlikely there will ever be a slew of Harry Potter or Lord of the Rings memorabilia, not only because so many of the effects and characters are computer-generated, but because the studios are more savvy about letting such valuable property on to the market.
So now may be a very good time to delve into movie memorabilia - before the digital age threatens to kill it off.