Alan Solem had a two-part article on the medical relevance of mollusks which included the hazards of consuming large radulae.  Radulae are relatively tough, so they do not digest easily, and many are designed for rasping on hard rocks.  Thus, a bunch of limpet radulae in the stomach is sort of like having a hairball with rough edges in your tummy.

Large chitons probably pose similar hazards.  I found a pile of empty shells once in the Bahamas, accompanied by the radulae, evidently discarded as inedible.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa