The lined chiton (Tonicella lineata) has colourful wavy lines on its shell plates, and markings on the girdle, both of which are highly variable. This can make it difficult to tell the difference between a lined chiton and a similar looking blue-lined chiton (Tonicella undocaerulea). In comparing the head plates of both species (head shell plate in this photo is at the top), the lined chiton has thicker lines of colour edged with thin dark brown lines, and these thin dark brown lines are absent on the head plate of a blue-lined chiton. The lined chiton grows to about 2 inches (5 cm) in length, with a range from the Aleutian Islands in Alaska to Channel Islands in California.
Reference:
Fretwell, Kelly and Starzomski, Brian. “Lined Chiton, Tonicella lineata” Biodiversity of the Central Coast, University of Victoria, 2013, https://www.centralcoastbiodiversity.org/lined-chiton-bull-tonicella-lineata.html
