Complex structures break in interesting and unexpected ways. This is applicable to both sea shells* and civilizations. Some results are prettier than others.
Two books I greatly enjoyed on the subjects of civilizations breaking are The Inheritance of Rome by Chris Wickham (which we’ve mentioned here and here) and 1177 BC by Eric H. Cline (which we’ve reviewed here), who capture the overwhelming complexity of events that conspire to change even the most solid appearing structures.
One book I did not enjoy on the subject was Collapse by Jared Diamond.
*down by the sea-shore