The lure was discovered in 2001 by Nora Needham of Slipper Island. Daughter Christina Needham - who now holds the lure - said Nora's son had been doing earthworks around the Home Bay house when she saw it unearthed by the bulldozer and picked it up. It was identified at Te Papa Museum on April 17.
Archaeologist Warren Gumbley described the lure as an "extraordinary artefact" and said the island was among the top 10 archaeological landscapes in the country.
However it is unlikely that the find - however significant - will thwart the island's sale.
Numerous sites on Slipper Island are registered with the New Zealand Archaeological Association including eight pa, various midden or rubbish dumps, and terraces. However none is listed with the Thames-Coromandel proposed district plan, which would give the site greater protection against development, and there are no registered wahi tapu sites, despite the island being considered wahi tapu, or sacred and precious, to the Ngati Maru Runanga and Ngati Hei iwi.
"The range of artefacts recovered over time from Slipper Island is revealing," said Mr Gumbley, who has recommended detailed surveys of identified archaeological sites and more work to identify previously unrecorded or potential archaeological sites.
"I think it's probably in the top 10 archaeological landscapes in the country. New Zealand is part of Polynesia and this is a tangible artefact that makes up part of the Polynesian migration story. The remains of early settlement from this colonisation phase is stretched all along Slipper Island. It's a remarkable landscape, it's almost unique in New Zealand."
A pearl shell lure similar to the one found on Slipper was unearthed in nearby Tairua Harbour in 1964 and is now housed at the Auckland Museum.
Ngati Hei spokesman Joe Davis said his tribe had been contacted about the sale a week earlier and although concerned about the possibility of development causing damage to wahi tapu sites, they were powerless to prevent the sale.
"Yes, we will continue to try to protect our cultural values, but not to try to halt a sale for some personal grievance. It's not even tribal, it's a normal transaction and there's nothing we could have done to influence that."
Tairua elder Reremoana Jones' great-great-great-great grandfather Tuokiokio was the last Maori chief, or rangatira, of Slipper Island. She said Slipper Island is known as Whakahau to Maori and considered wahi tapu, or sacred to the Ngati Maru Runanga and Ngati Hei. The island was once a battlefield that should be treated with respect.
"There was a lot of killing that went on out there, that whole island is very tapu. What scares me is that it will be built on, perhaps by new owners who have children and they are innocent. They need to be warned."
Thames-Coromandel District Council is considering submissions to its proposed District Plan on the need to protect the island's archaeology.
The hearing panel would consider these submissions and any evidence presented at a hearing before making any recommendation to include additional archaeological sites in its archaeological sites schedule.