When I first came up with the general notion of writing a book about microbes, I had about six “cases” that I thought were really interesting and should be written about. Life being what it is, about half of these originals failed to make it into the finished product.

One of these discarded originals was a bit about magnetic bacteria. It’s a good story – how they were discovered, what the point of them is, a new controversy popping up in 2006… great stuff, with the best bit just the fact of their existence; microbe magnets – reality bordering on absurdity, which is how I like it.

And now we see that magnetic senses may be even more widespread than we thought. Microbes, okay, they have all sorts of stuff, so why not magnets. Migrating birds, yes, fair enough, how else could they navigate…

but cows?