Building a home, the ‘modification of the environment to suit the species’, is often said to be a hallmark of very highly developed animals. Of course, it applies to we humans; but then it also applies to nest-building birds. Some fish can construct a home out of gravel or weed. Spiders build webs; bees make nests. But microbes? Could they construct something like a home? Amazing as it may seem, this astonishing propensity was first reported on 14 November 1704, in a letter sent by the pioneering Dutch amateur microscopist Antony van Leeuwenhoek to the Royal Society of London. With his letter he sent a drawing of a rotifer we now call Floscularia ringens (left). It makes its shell from tiny round granules, intricately cemented together.	INGENIOUS MICROBES THAT BUILD THEIR OWN HOMES	Still, nobody knows how. Rotifers are microbes (because you will need a microscope to study them) but they are composed of more than one cell. Yet they are ingenious enough to manipulate material and so to construct their own homes. This is a remarkably adaptable species. But more amazing by far are the single-celled organisms that can do this. Some simple amoebae can make a shell out of tiny ‘bricks’! Yes, single-celled organisms can select the right building materials, arrange them all into a perfect shape (with nothing but jelly-like pseudopodia to do it with) and cement them carefully together. Just imagine the complex processes of recognition and manipulation involved. A human needs training to do this; single cells do it by themselves. ‘Simple’, hey?