Salt

Salt, chemically known as sodium chloride, was one the essential chemical compounds for the creation of life. As well as being an essential sustainer of life, it was also the most common spice in the galaxy.

On planet M-113, the M-113 creatures had evolved the ability to drain salt from a prey's bodies via suckers on their hands, and it would sustain them for a time. When the crew of the USS Enterprise encountered the last surviving creature in 2266, several crewmen were killed. (TOS episode: "The Man Trap").