Welcome to the Apostrophe Protection Society The Examples menu is where all the action is. However, you'll need to have Flash installed to see the examples - a wee bit annoying if you use an iPad like I do!
The common spiral shape immediately brings to view the action of rotation. Water winds its way down the drain in a sink. Moist air spirals its way into the low-pressure center of a hurricane. Even the rotation of a galaxy imprints its structure in the form of dense spiral arms that trace regions of star formation.