The Kalandan homeworld was a formerly inhabited planet, and was the homeworld of the extinct Kalandans.

A few thousand years before 2268, in building an outpost, the builders inadvertently created a deadly organism. The advanced force on this outpost was destroyed by this organism; its last survivor, Losira, recorded a welcoming message for those of her people who had, by then, ceased to exist, then enabled the outpost's automatic defenses to guard it against all non-Kalandan life forms.

Doctor Leonard McCoy theorized that when a supply ship arrived at the outpost, the crew became infected, and that this caused the infection to spread through Kalandan territory, all the way back to the homeworld where it killed the last survivors and caused the extinction of the Kalandans. (TOS: "That Which Survives")