The fossils that scientists claimed were in the Martian meteorite were so small that 50,000 of them could fit across the width of a human hair. They were far smaller than any bacteria found on Earth.

Since that time not many scientists have been prepared to believe that they are truly fossils rather than peculiarly shaped mineral deposits.

Many have wondered if there are any more microfossil structures in any of the 12 known meteorites from Mars. The problem they have is that searching for them with a powerful microscope would take far too long.

Are there fossils in these rocks?

Now researchers are hoping to use thousands of computers belonging to volunteers on the Internet.

"We hope to get young scientists from elementary school through college to help us with the search by linking their computers to ours," said Dr David Noever of Nasa.

Dr Noever hopes to use a sophisticated series of computer programs to learn what various types of microbial life look like and use that knowledge to look for life-like structures in the Mars rocks.

One of the main challenges of the task is that many things that look life-like are not life forms and many true life forms do not look life like at all.

Developing one powerful computer to carry out this task would be too expensive so it is hoped that thousands of personal computers could work together instead.

A similar technique has already been tried by astronomers looking for signals from extraterrestrial intelligence in space.

Data from radio telescopes involved in the search has been shared among hundreds of people who perform a part of the analysis on their personal computers.