Dentic

Dentics are small creatures with a fluorine based biology, comparable in shape and size to leeches on Earth. Unlike leeches, dentics do not consume blood; rather they feed off the food remnants and bacteria in the mouths of larger species, making them highly desirable for starship crews

As such, a practical and symbiotic use has been found for them. Putting one in the mouth acts to clean teeth as they eat all food remnants and bacteria, prevent gum disease and even give a minty breath, thanks to the mint-smelling urine of the creature.

They are inedible raw, and possibly poisonous/internally harmful when ingested (a luxan stated to a human when first using a Dentic tells to NEVER swallow a dentic, though it's possible the admonition might have also been intended to preserve a limited supply) but can be eaten when heavily fried, but even then they have an unpleasant taste.