The structures being studied are so small that nearly a billion could fit on the head of a pin. Many scientists doubted the finding, saying the features could have been created on Earth or might not have indicated microbial life at all. Researchers have debated the evidence ever since, and though there is wide agreement that the structures were created on Mars, the debate continues as to their origin. The newly found chains were formed inside organic material which has a structure that held the crystals together, the researchers say. Each magnetite crystal in the chain is a tiny magnet, approximately one-millionth of an inch in diameter.
Magnetite is an iron oxide, similar to iron rust.
The chains may have served as compasses for bacteria that would navigate with the help of the magnetic crystal chains inside their bodies. The organisms are referred to as magnetotactic bacteria. The chains were preserved in the meteorite long after the bacteria themselves decayed, the researchers say. The scientists say the magnetite chains probably were flushed into microscopic cracks inside the Martian rock after it was shattered by an asteroid impact approximately 3.9 billion years ago. This cataclysmic event on Mars surface also may have killed the bacteria.