I went to a zoo recently and saw a couple of toucans (in very small enclosures.. grr). They each had cracked beaks. Would they have cracked if they had been in the wild, and how did they crack them (was it due to stress?).

Vandals regularly smash the windows of our local railway station, and they are equally regularly replaced with laminated glass consisting of two sheets with a flexible layer between.

When the windows break (see photo), the glass on the side the stone came from cracks in concentric circles, but the other layer cracks radially, together forming a spiderweb pattern. Why is this?

Hugh Young, Pukerua Bay, New Zealand