I attended a colloquium talk on Thursday at the Institute I’m visiting for a couple of days. It was a colloquium on interesting magnetic orderings. There I learned that there are many species of bacteria that produce single domain magnetic crystals of high purity.
Here is a link with some of that information. It seems that this helps the bacteria determine the up and down direction: a really difficult problem in aquatic media. Sometimes it would be really cool to be equipped with such an extra magnetic sense (especially if I get turned around in a city I don’t know). We people fake it by GPS devices or by having a compass, but who walks with a compass nowadays anyway? Also, your favorite GPS device might run out of batteries…
In any case, I often get amazed by such facts
Shores of the Dirac Sea 