What are trilobites?

                     Trilobites are another of the great groups of animals that lived 500 million years ago, but have now disappeared. They looked rather like large flattened woodlice (pill bugs). Some trilobites were predators, but most were scavengers that scuttled around on the sea-bed on their many jointed legs. Some grew to a length of 45 cm and weighed about 4.5 kg, but most were much smaller. Like woodlice, trilobites could roll up into a ball when threatened. The name ‘trilobite’ comes from the animal’s appearance — its body was in three lobes. Trilobites were arthropods (animals with jointed skeletons), and like modern crabs and lobsters they had to split their rigid shell and emerge before they could grow bigger.