The deep *vertical* lines in your fingernails are genetic. If you have *horizontal* ridges in your nails, you should see a doctor.
dirt
smoking
picking warts on your bum and casual worms.
Keratin... it's a natural substance that makes the nail harden.
Fingernails are normal in the human body. Please be more specific in your question.
The rivets in the titanic were made of iron.
The white area in fingernails and hair are caused by air. That's why snow is white and not blue. Little bumps and bruises that are done to the bed of the nail cause these imperfections.
the Eiffel tower has 2.5 million rivets or 2500000 rivets
25000 rivets were rotten on titanic
The duration of Rhapsody in Rivets is 420.0 seconds.
42,687 rivets, I counted them