Ischnochiton elongatus is a very common, and very variable species of chiton, usually found under rock. It can be difficult to distinguish from other ischnochitons, including I. subviridis, I. versicolor, I. variegatus and I. thomasi. It has small girdle scales, fine sculpturing on the valves, and a wide range of colours and patterns. This species can commonly be found in mottled green/yellow/brown, plain colours (often with a central white stripe) or alternating wavy black and white lines.
