These tiny magnetic crystals (figures a, b,c and d) help the bacteria to navigate.
Scientists have shown that tiny crystals found inside bacteria provide a magnetic compass to help them navigate through sediment to find the best food.
Researchers say their study could provide fresh clues to explain biomagnetism - a phenomenon in which some birds, insects and marine life navigate using the magnetic field that encompasses the Earth.
The study focuses on magnetotactic bacteria, which contain chains of magnetic crystals, called magnetosomes. They exist all over the globe, living in lake and pond sediments and in ocean coastal regions.
Since the discovery of magnetotactic bacteria in the 1970s, it has not been clear exactly what magnetosomes were for. Previous research suggested that some magnetosome chains would not be useful for navigation because their crystal sizes did not possess the right magnetic qualities.