Cryptoconchus porosus, or the butterfly chiton, is a species of large chiton or "coat of mail shell", a marine polyplacophoran mollusk in the family Acanthochitonidae.
This species of chiton is endemic
to New Zealand
This is a large, long, thick, and fleshy chiton, with a sky-blue or occasionally pinkish or orange tinged valves
, hidden under the girdle
, which varies from dull orange to dark greenish.
The length is 73 mm, and width 33 mm, but these measurements are from a dried specimen, and the animal is much larger in life.