| Arches are so strong that arches in buildings constructed by the Romans nearly 2000 years ago are still standing in good condition today.
 The largest hen's egg ever recorded weighed 453 g (1 lb) and had a double shell. The strong arch form can still be seen in modern structures such as bridges made of steel or concrete. 
Most of the hard part of an eggshell is made of calcium - the same material found in teeth and bones. Calcium dissolves in acid, so if you leave an egg in vinegar (which is an acid) for a few days, you will end up with a shell-less egg! |
