The marine relatives of woodlice, hoglice and water fleas comprise the majority of the huge group called Crustacea. They include crabs, prawns, lobsters and lice. Nearly all have beautiful and bizarre youngsters or larvae and amongst their numbers are very colourful, very mechanical-looking and often elaborately advanced designs. Spines, hooks, spurs and whiskers are commonplace – some used for defence, others for prey capture, others for locomotion, aerating gills or wafting currents of food-laden water past their mouths. All have well-developed compound eyes – a bit like an insect but not quite so elaborate. Many have head and shoulders fused together into a very strong cephalothorax. These are the bulldozers of the plankton community and these tough outer cases have remained efficient protective devices on their kith and kin since before Cambrian times (600,000,000 years ago).