(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.

The researchers said the fossils – about 50 times smaller than the width of a human hair – are made of a strongly magnetic iron-bearing mineral called magnetite. They suspect these particles were once part of a marine organism, though its identity remains mysterious.

Scientists have recovered a number of these fossils dating back as far as 97 million years ago. There has been a debate as to whether or not they were biological in origin.

A new study employed three-dimensional imaging to determine the magnetic structure of one of the fossil

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