Zoology 10th Edition by Stephen Miller,John Harley

Exercise 17

Members of the class Polyplacophora attach to hard substrates in shallow marine environments using their muscular foot. They have a shell consisting of eight dorsal plates and feed by rasping algae from their substrate. The nervous system is ladderlike and development is external with a trochophore larval stage.
What features of members of the class Polyplacophora (if any) would be considered atypical of molluscs in general?