Is a leech a mollusk

No leeches are definitely not Mammals. Leeches are annelids comprising the subclass Hirudinea. There are fresh water, terrestrial, and marine leeches. Like the Oligochaeta, they share the presence of a clitellum. Like earthworms, leeches are hermaphrodites. Some, but not all leeches feed on blood.

en.wikipedia.org/wiki/Leeches