Porcupine quills are hollow, like feathers, and are made from the same material, but then so are hairs, and fingernails, and claws and scales. The quill is a unique adaptation of one of nature's commonest substances and it varies even among porcupines.African porcupines can weigh as much as 60 pounds and have quills as thick as soda straws. Martha Foley and Dr. Curt Stager talk about "prickly" matters.