An auctioneer called in to help clear an Essex house said he had "an Indiana Jones moment" when he discovered an ancient Egyptian sarcophagus lid propped up in a dusty corner.
Stephen Drake from Willingham Auctions in Cambridgeshire found it covered in cobwebs in a Bradwell-on-sea house.
Cambridge University's Fitzwilliam Museum told him the coffin was about 3,000 years old, he said.
It is expected to fetch several thousand pounds at auction next month.
Mr Drake said relatives of the deceased homeowner had no idea where the partial sarcophagus had come from.
'Whip and trilby'
"The house was being refurbished and was like a bomb site," Mr Drake said.
"The only way in was through a hole in the wall. When I peered through I saw this amazing sarcophagus covered in dust and cobwebs."
Helen Strudwick, an Egyptologist at the Fitzwilliam Museum, said: "It is a very rare object to see appearing in a local context like this. It would be great to know more about the history of how it reached the UK."
Discovering the sarcophagus was "an exciting find", Mr Drake added.
"It really felt like a scene from Raiders of the Lost Ark. I wish I'd had my whip and trilby with me."
Mr Drake said he had asked an expert at the British Museum to comment on the age and historical significance of the sarcophagus.