Sentient tar
Sentient tar was a term that Commander Jack Ransom used to describe an intelligent lifeform he had encountered on a past away mission.
In 2380, preparing for a gift-delivery mission to Gelrak V, Ransom listed a disaster with sentient tar among dangerous away missions he had been on that were expected to have gone smoothly. (LD: "Temporal Edict")
This lifeform was only mentioned in dialogue.
This may be a reference to Armus, a being encountered on an away mission by the crew of the USS Enterprise-D, and later tormented by the lower deckers aboard the USS Cerritos.