Why don't your eyeballs freeze?

[We put this question to David Thomas, author of 'Surviving Antarctica']Because your eyeball is contained within your head, and your head is kept at body temperature, it never gets cold enough to freeze. The eyeballs in a dead body would indeed freeze, but while you're alive and radiating heat it can't. Even tears wont freeze immediately, as they are very salty, and salt reduces the freezing point.