Unusual three-way bestows magnetic sense to single-celled organism‎

How do microorganisms orient themselves to find the optimal habitat? Scientists have thoroughly investigated so-called magnetotactic bacteria, which use the Earth's magnetic field as a biological compass. Some eukaryotic single-celled organisms—that is, more complex organisms like ciliates, which, unlike bacteria, have a cell nucleus—also possess this capability. But how they acquire it has largely remained a puzzle.