This is needed both for courage and hardcover books.

Answer: spine

More Difficult Riddles with answers

More Difficult Riddles

This is rectangular, hollow and has a lid, and where you’ll find it you might wonder, it is just six feet under. What is it?
This only turns over once you have traveled very far. What is it?
This only turns over once you have travelled very far. What is it?
This thing runs but cannot walk, sometimes sings but never talks. Lacks arms, has hands; lacks a head but has a face.
This veggie is characterized of long stalks or shoots taken from the plant. They have a strong odor when cooked and can influence the color or urine
Though blind as well, can lead the blind well.
Though easy to spot, when allowed to plume, It is hard to see, when held in a room.
Though I have neither legs nor feet, my use is for to go; Although I cannot speak, I tell what others want to know
Though I wander the earth, I am no longer here. I am pale and I chill everyone near. Who am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.
Thousands lay up gold within this house, But no man made it. Spears past counting guard this house, But no man wards it.
Thousands of these come together to make a digital image. What is it?