1) Backs of books 2) Book ends 3) Book parts 4) Book stiffeners 5) Bookcase lineup 6) Bookshelf display 7) Echidna features 8) Library patrons read them 9) Mollusks lack these 10) Parts of books 11) Places for book titles 12) Places for titles 13) Quills 14) Sets of vertebrae 15) Sharp plant parts 16) Things seen on a bookshelf 
Horn-like projections formed upon a lava dome.
Horn-like projections formed upon a lava dome.
Horn-like projections formed upon a lava dome.
a sharp-pointed woody structure, usually a modified leaf or leaf part.
Horn-like projections formed upon a lava dome.
a sharp, projecting part on an animal