Afossil is a. an imprint in stone of something that once lived. b. an ancient way of writing, carved into stone or stamped into clay. c. something that human beings learned how to make and use. d. a written record.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.