What is "whorling"

Usage examples of "whorling".

You name it, and it spits it up some time or other: a dead man, a shell that might be alabaster, rose and pumpkin bright, with a sinistral whorling, rising inevitably to the tip of a horn as innocent as the unicorn's, a bottle with or without a note which you may or may not be able to read, a human foetus, a piece of very smooth wood with a nail hole in it--maybe a piece of the True Cross, I don't know--and white pebbles and dark pebbles, fishes, empty dories, yards of cable, coral, seaweed, and those are pearls that were his eyes.