An American aquarium says it intends to auction a rare two-headed albino rat snake for $150,000 (£87,000).
The World Aquarium in St Louis has been home to the unique reptile, named "We", for the past six years.
Aquarium president Leonard Sonnenschein said he hoped the snake would generate as much demand on the eBay auction site as a priceless work of art.
However eBay bans the sale of live animals and says if the creature is listed it will promptly be removed.
A spokesman told the BBC News website: "It is against eBay policy to sell this on the site. We can't stop them from listing this snake, but we've told them we'll pull it down immediately."
An aquarium spokeswoman said conditions were in place to make sure the snake went to a responsible buyer.
We was being sold to pay for education, conservation and research programmes, the aquarium said.
The aquarium purchased the snake for $15,000 (£8,700) when it was six-and-a-half years old, despite knowing that most two-headed snakes do not live for more than a few months.
"It's an amazing snake," Mr Sonnenschein told the Associated Press news agency. "When people see it they are awe-struck."
The snake is a healthy size for a rat snake, at 2.5cm (one inch) thick and 1.2m (four feet) long.
It is currently at the prime age for breeding and is expected to live for another 10 to 15 years.
It has survived for so long because both heads are connected to the same stomach, Mr Sonnenschein added.
We was almost sold in 2004, after it was stolen by a city museum worker. Fortunately, authorities found the snake in the man's garage at his home in Illinois.
Mr Sonnenschein said the man was intending to sell it.