The Lactrans resembled giant slugs
A slug was a shell-less mollusk found on several planets, including Earth and Ferenginar.
The Ferengi considered slugs to be delicacies and slug steaks were a popular meal. A Ferengi saying regarding lost love was, "There are other slugs in the sea." (DS9: "The Ascent", "Ferengi Love Songs")
In 2369, Commander Benjamin Sisko called Dax a slug. He asked Jadzia if she had told Doctor Bashir "about that slug inside you." (DS9: "Emissary")
In early 2373, Morn had a breakfast of raw slug liver. (DS9: "The Assignment")
When stranded with Odo on a planet later that year, Quark lamented the lack of slugs there, as well as beetles, worms and snails. (DS9: "The Ascent")
Giant slug attacking Tendi
In 2381, Ensigns D'Vana Tendi, Beckett Mariner, and Sam Rutherford found an alien slug during anomaly consolidation duty on the USS Cerritos. When the slug was accidentally broken out of its sample container, it rapidly grew to an enormous size and swallowed Tendi whole. Mariner and Rutherford managed to pull Tendi free when the slug began to excrete her; Mariner then used a hypospray to revert the slug back to its original small form. (LD: "The Spy Humongous")
In an alternate 2390s, Nog joked that he would prefer the slugs of the Louisiana bayou to redfish. (DS9: "The Visitor")