The whelk is a type of sea snail, particularly referring to those of the family Buccinidae. While on vacation in the Isle of Wight during July of 1991, Marjorie Dursley ate a "funny" whelk and thus fell ill, most likely of food poisoning. She wrote a postcard to her brother Vernon to inform him of this occurrence.
- Harry Potter and the Philosopher's Stone (First mentioned)
- Harry Potter and the Philosopher's Stone (film) (Mentioned only)