Possible Clues:

• Back-bones
• The way to start at the start of the month with the thing I swallowed
• They point to the wood in the ship
• Sea urchin's protection
• Are they sharp enough to make some deal among the saints?
• Places to find literary titles
• Backbones yielding steaks with 31
• The tree in the ship points to them
• Book ends
• Bookbinder's supply