1. Galvanized metal nails get a zinc bath. Metal construction nails used outdoors are often galvanized—meaning they are dipped into liquid zinc melted to over 800°F (425°C). The zinc coating shields the steel underneath so it won't rust in the rain!

2. Twisted nails helped hold the Titanic together. Over 3 million iron and steel rivets and heavy nails were hammered into the famous ocean liner Titanic. Blacksmiths and shipbuilders used custom-shaped metal fasteners to hold massive steel plates to the ship's frame!

3. Masonry nails are hardened like armor. Unlike soft steel wood nails that bend easily, metal nails made for driving into concrete or brick walls are high-carbon steel heated to extreme temperatures, making them nearly impossible to bend under heavy hammer strikes.

4. Ancient metal nails were as valuable as money. Before factory machines were invented, metal carpentry nails had to be hammered out one by one by hand by a blacksmith. They were so valuable in early American history that people sometimes burned down old houses just to collect the metal nails left in the ashes!

5. The Romans used nails as ancient magic charms. In ancient Rome, people believed iron nails had mysterious powers. They would bend iron nails into shapes and bury them under doorways or wear them as amulets to ward off bad luck!

6. Penny sizes tell you how big a nail is. Construction nails are often measured in "pennies" (written with a "d", like 8d or 16d). Hundreds of years ago in England, this named how many pence it cost to buy a hundred nails of that size!

7. Automatic nail guns fire faster than a heartbeat. Modern pneumatic nail guns used in construction use compressed air to blast heavy steel nails into thick wood studs in less than 0.1 seconds, driving thousands of nails a day with zero hand-hammering!