Urna was a formerly inhabited planet.
In the 23rd century, Urna was an industrial seat, a hub for the enrichment of unstable metals. At the time, the Federation began sounding alarms that toxicity from these activities would thin the atmosphere, resulting in increased levels of UVB radiation that would trigger mutations in the native lifeforms. Seeds from Urna were stored aboard the Federation seed vault ship USS Tikhov.
The Federation's warnings eventually came to pass, and Urna experienced an environmental collapse. By 3189, it had been deserted for centuries. That year, a group of Kili stopped by the planet and ate plants from the surface that infected them with life-threatening prions. The USS Discovery was able to obtain unmutated Urna seeds from the Tikhov that allowed the synthesis of an antidote. (DIS: "Die Trying")