A rock from outer space will keep its secrets after scientists abandoned plans to split the ninth meteorite ever found in New Zealand.

A tiny, protruding shard of green gemstone olivine is likely to be the only glimpse of what remains locked inside the 4.5-billion-year-old rock.

It hurtled through the atmosphere and landed in the living room of Auckland couple Phil and Brenda Archer last weekend.

Planned tests to determine exactly what the Ellerslie Meteorite is made of were dropped after it emerged too much of the 1.3kg rock would need to be lopped off to carry out the examination.

It is thought that more olivine, known as peridot in its gemstone form, would be inside.

But Dr Joel Schiff, Auckland University lecturer and editor of Meteorite Magazine, said neither scientists nor the Archers were willing to see the rock pulled apart.

But that has not stopped meteorite fever taking hold.

A woman turned up at the Auckland Observatory this week with a piece of tar, convinced it was a genuine meteorite.

And a Lawrence man who planned to sell a "meteorite" found in the 1950s has had his plans dashed by scientists who say it is not from outer space.

Meanwhile, a bidding war is under way for the Ellerslie Meteorite.

Auckland's Stardome Observatory has offered $500 to hire the rock for a month - and the sofa it damaged when it crash-landed into the Archers' home.

Jenny McCormick, education officer at the observatory, said the hire offer was a temporary move while staff came up with ways to buy the rock.

"We want to keep it here because of its importance as early solar system evidence," said Ms McCormick.

Auckland Museum is also trying to raise cash to keep the extra-terrestrial arrival in New Zealand.

A museum spokeswoman said they were liaising with the University of Auckland to get a good understanding of the meteorite's significance and composition.

"It is a good fit because we already have quite a good collection of meteorites, but the price would need to be realistic and affordable," she said.

But the both organisations face stiff competition from overseas buyers - one of whom has offered $25,000 to buy the meteorite.

The man, from the United States, has offered US$15,000 as a starting bid and indicated that he would be prepared to hand over more money.

The rock itself is wrapped in cloth and tucked away "in a safe place".

Mr and Mrs Archer, who found themselves in almost every newspaper in the world after it ploughed through their roof, have so far refused to sell.

They would prefer the meteorite, which was described by Mr Schiff as a national treasure, to remain in this country.

"But unfortunately money does talk," said Mrs Archer.

"I'm astounded that people will pay so much for a piece of rock."

NZ meteorites

* Meteorites discovered in New Zealand are covered by the Antiquities Act and may not be exported without written permission from the Ministry for Culture and Heritage.

* There are only nine meteorites confirmed to have fallen on New Zealand: Wairarapa 1863; Makarewa 1879; Mokoia 1908; Morven 1925; View Hill 1953; Waingaromia 1970; Dunganville 1976; Kimbolton 1976 and Ellerslie 2004.

* Apart from Ellerslie only one other (Mokoia) was seen falling. The others have mainly been found by farmers working their paddocks who have noticed unusual rocks.