This juvenile giant Pacific chiton (Cryptochiton stelleri) can be recognized by the bristles found on its dorsal surface. It seems most juveniles do not have such an abundance of bristle clusters, so this 1 inch (2.5 cm) long chiton was an interesting find.
The giant Pacific chiton is the largest chiton in the world. Its eight shell plates, usually exposed on other chitons, are completely covered by the bumpy textured girdle. Its colouration varies from brown to deep red, with occasional lighter areas, and this dark colour is derived from the red algae living on the chiton, as well as red algae consumed. The belly/ventral side of the giant Pacific chiton is yellow or orange. The radula, used to scrap algae off of rocks is covered in a very hard magnetic mineral called magnetite. The giant Pacific chiton can grow to 14 inches (35 cm) long, with a range that includes Japan, Kamchatka in Russia, Aleutian Islands in Alaska to Channel Islands in California.
References:
Fretwell, Kelly and Starzomski, Brian. “Giant Pacific Chiton, Cryptochiton stelleri” Biodiversity of the Central Coast, University of Victoria, 2013, https://www.centralcoastbiodiversity.org/giant-pacific-chiton-bull-cryptochiton-stelleri.html
Lamb, Andy and Hanby, Bernard. Marine Life of the Pacific Northwest: A Photographic Encyclopedia of Invertebrates, Seaweeds and Selected Fishes. Madeira Park: Harbour Publishing, 2005. (An online version of this book is also available to subscribers at https://knowbc.com)
