Anything vermiform is long, skinny, and tube-shaped, like a worm. Snakes, earthworms, and even the human appendix can be described as vermiform.
The term vermiform is used by scientists to describe worms and worm-like animals — it comes from two Latin roots, vermis, "worm," and forma, "form or shape." So a biologist might describe vermiform leeches in a lake or an infectious disease specialist might diagnose a patient with a vermiform parasite like pinworms. Sometimes body parts with this general shape are also called vermiform, like the vermiform appendix that most humans have.