Peter Baye explored some of the tide pools at low tide at the Stornetta Public Lands. He found many wonders. One of them was a Gumboot Chiton, Cryptochiton stelleri, also called a Giant Pacific Chiton.
And here is the underside of this large Chiton.
Gumboot Chitons eat algae, moving along rocks. They also eat sea lettuce and giant kelp. They can live up to forty years. It seems they have no predators to worry about. They are edible but apparently so unpalatable that one would have to be starving to eat it. "Rubbery" is how they are described.
To read about the wonderful Stornetta Public Lands, here's the link to a previous post: http://www.mendonomasightings.com/2012/02/18/low-tide-at-the-stornetta-public-lands-in-point-arena-breathtaking/