The Devil in the Dark

Dispatched to the mining colony on Janus VI, the Enterprise is tasked to investigate rumors of a strange, subterranean creature responsible for destruction of equipment and the deaths of fifty miners. Kirk and Spock discover a silicon-based life form, a Horta, which lives in the surrounding rock. After wounding the creature, Spock performs a mind meld, discovering the reason behind the Horta's attacks.[37]