Spiked and studded dog-collars derive from the days of the Ancient Greeks, who would give their sheep-dogs sharply spiked collars to protect their necks from wolves whilst they watched over a Sheppard's flock at night.

The external tank on space shuttles is not painted. It is the only part of the shuttle that is lost after launch, so it is not necessary to worry about metal corrosion.

A spider's silk is stronger than steel.

AMAZING FACTS