While You're Waiting for the Food to Come by Eric Muller, Illustrated by Eldon Doty Hardcover version Paperback version To order or find out more about this book, click on the book cover above or on either cover version. Challenge some one to break an egg in the palm of their hand. Bet them that they can't do it by squeezing the egg with their palm and fingers. Have them slowly curl their fingers around the egg and start squeezing. By wrapping your fingers around the egg, pressure is evenly distributed throughout the shell.
Eggshells are incredibly strong for their weight.
The spherical shape of the eggshell maximizes strength with a minimum of shell material. If you want to break the egg, you'll need a ring. The small contact where the hard metal ring and shell meet is an area of significantly higher pressure. This uneven distribution of pressure will vary likely cause the eggshell to crack. Do Science 2000.