@Maggie here is a segment from Sarah McAnulty's (PhD grad student and speaker at TonmoCon VII) latest "Skype A Scientist" Youtube Q&A that just happens to help explain a radula. The forum software removes the starting point so I am including a manual link to the section on the radula, however, you may enjoy the entire talk.
Thanks for the video! I follow Sarah McAnulty on Instagram but didn't realize she had a youtube channel! She's so friendly and knowledgeable!