Birds make heroic journeys guided by the Earth's magnetic field, but how they detect magnetic fields has puzzled scientists for decades.
Now the Keays lab at the Research Institute of Molecular Pathology in Vienna has added some important pieces to this puzzle.
Their work reports the discovery of iron balls in sensory neurons. These cells, called hair cells, are found in the ear and are responsible for detecting sound and gravity.
Remarkably, each cell has just one iron ball, and it is in the same place in every cell.
"It's very exciting. We find these iron balls in every bird, whether it's a pigeon or an ostrich" added Mattias Lauwers who discovered them "but not in humans".
It is an astonishing finding, despite decades of research these conspicuous balls of iron had not been discovered.
This finding builds on previous work by the lab of David Keays who last year showed that iron-rich cells in the beak of pigeons that were believed to be the magnetic sensors, were really just blood cells.
"These cells are much better candidates, because they're definitely neurons. But we're a long way off to understanding how magnetic sensing works - we still don't know what these mysterious iron balls are doing." said Dr Keays.
Their work was published in Current Biology. (ANI)