Talin IV had at least four major continents, with the largest comprised largely of equatorial desert, and the second largest covered by forest and grasslands. The fourth-largest continent held an anomalous large deposit of naturally-occurring rubindium crystals.
Talin IV also had a single moon.
In the mid 2250s, shortly after Talin science discovered a method of nuclear fission, an ancient, primitive lifeform dubbed "the Many", were attracted to Talin IV, and began manipulating the natives' technology in an effort to increase political tensions and provoke a large release of atmospheric radiation.
In 2269, the Many succeeded in triggering a major exchange of nuclear weapons, creating a new planetary environment fit to grow a certain strain of purple waterborne algae, intended for consumption by a symbiotic lifeform, called "the One". However, the Federation intervened, launching an anticipated three-year project to remove this growth (which would instead be cultivated on Talin VIII, a gas giant in the Talin system) and restore the planet's biosphere. (TOS novel: Prime Directive)