The serpent worm was a lifeform that served as the main ingredient of gagh, a Klingon delicacy. (TNG: "A Matter Of Honor", DS9: "Sons and Daughters")
In 2373, a serpent worm was delivered to Deep Space 9, where the tentacle of a creature grabbed Kira Nerys' hand. (DS9: "A Simple Investigation")
According to Klingon for the Galactic Traveler by Marc Okrand, and according to the video game Star Trek: Klingon, serpent worms are referred to as "ghargh" (or "gharghmey") before being prepared into gagh.