No. 68: Mar-Apr 1990
It is already well-established that saltand fresh-water sediments harbor bacteria that synthesize grains of magnetite - presumably for the purpose of sensing the ambient magnetic field and orienting themselves. Similar bacteria have recently been discovered living in ordinary soil in Bavaria. It is near-certain that they will now be found just about everywhere. J.W.E. Fassbinder et al, who reported the Bavarian bacteria, conclude their Abstract with: "We suggest that the magnetic bacteria and their magnetofossils can contribute to the magnetic properties of soils."
(Fassbinder, Jorg W.E., et al; "Occurrence of Magnetic Bacteria in Soil." Nature, 343:161, 1990.)
Comment. It is easy to reach great heights of speculation given the facts that: (1) magnetic bacteria exist; (2) bacteria in general are exceedingly abundant; and (3) bacteria are found deep inside the earth's crust and, seemingly, just about anywhere one cares to look. Now, let's see how ridiculous one can get:
Imagine the consequences if any one of the above speculations is even close to the mark!