I hope you will excuse me starting by talking about myself but it might help to explain some of my background and how I came to write this book. When I was doing my bachelor's degree in Zoology at the University of Bristol in England, one of my final year projects was on the structure of the eggshell, and the hatching mechanisms of the eggs, of a nematode parasite of cockroaches that rejoices in the splendid name of Hammerschmidtiella diesingi (named after a German nematologist, Hammerschmidt). Nematodes are a group of worm-like invertebrate animals. The eggshell turned out to have complex systems of pores and spaces in its outer layers. I stayed on at Bristol to do a PhD that followed up this work and looked at the eggshells of a variety of parasitic nematodes. The nematode eggshell is one of the most resistant of all biological structures. In some cases, it can even survive immersion in concentrated sulphuric acid. The eggshell has a layer of lipid, which restricts the exchange of materials between the egg and its environment. The eggs lose water very slowly when exposed to desiccation, enabling the larvae enclosed within them to survive the total loss of water from the egg. The pores in the eggshell of H. diesingi are involved in this process.

The free-living stages of some parasitic nematodes (those developing after the hatching of the egg), and of some free-living nematodes, show extraordinary abilities to survive extreme environmental stresses. They will tolerate freezing, complete desiccation and exposure to chemicals that are fatal to most other organisms (such as the fixatives used to kill and stabilise specimens for microscopy).