A porcupine's quills are actually a special kind of hair, made of the same stuff as your fingernails - keratin. The quills are hollow, which makes them light, and very sharp. Normally they lie flat against the porcupine's body. But if anything scares the porcupine, the quills stand straight up and the porcupine looks twice as big.
Crested porcupines do not 'shoot' their quills, even though some old stories say they do. Instead, if a predator gets too close, the porcupine reverses into them with the quills raised. The quills come out easily, and a hungry predator usually goes home with a faceful of spikes and a strong lesson learned: don't bother that animal.
Porcupines spend the day asleep in burrows that they dig themselves. Their burrows can be huge - a network of tunnels and rooms going down two or three metres. They come out at night to look for food. They mostly eat roots, bulbs, fruit, bark and the bones of dead animals, which they chew on to get calcium for their quills.
Crested porcupines used to live mainly in Africa. Long ago, possibly with the help of the Romans, they spread north into Italy, and they have lived here ever since. Today you can find their tracks - and sometimes their dropped quills - in many Italian woods.