The gastropod Fusitriton oregonensis has a thick, hairy periostracum, which inhibits settling and growth of many borers and epizoans, This inhibitory effect could contribute to the snail's energetic efficiency by reducing energy utilized for repair of shell destruction caused by borers, and by reducing weight of encrusters carried during movement. Similarly, this deterrent to borers, and hence to shell weakening, could aid in resistance to predators which break the shell. Knowledge gained from studies of encruster inhibitor properties in molluscs may lead to development of a superior antifouling system.