Shells litter the beaches of every continent on our planet. They are durable enough to be used as building material, but they are so compelling that societies have featured their motifs in religion, art, and architecture. Many varieties of shellfish have the additional virtue of being delicious!
When you are growing up, there are two institutional places that affect you most powerfully -- the church, which belongs to God, and the public library, which belongs to you. The public library is a great equalizer.