Answer:
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. Sooner or later everybody needs my help yet many people are afraid to let me help them.
I row quickly with four oars but never comes out from under my own roof.
I am black within and red without With four corners round about.
I am a key that is playful. What am I?
The more you take the more you leave behind. What 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.