By Will Dunham(Reuters) -Microscopic magnetic fossils found in North Atlantic seafloor sediments may represent components of an internal “GPS system” for an ancient marine creature that used Earth’s magnetic field to navigate long distances, according to scientists. While some migratory animals including birds, fish and insects are thought to use Earth’s magnetic field to navigate, how they manage this remains unanswered. One hypothesis is that magnetite particles inside their bodies align with Earth’s magnetic field, akin to a compass needle. These particles closely resemble magnetite fossils called magnetosomes produced by certain bacteria, though magnetosomes are around 20 times smaller. As the particle reoriented itself with Earth’s magnetic field, it could have generated a mechanical or electrical signal that the organism used to detect magnetic intensity and direction,” Valencia said.