The creature in the Star Trek episode “The Devil in the Dark” is the Horta.
The Horta is a silicon-based life-form living beneath the surface of Janus VI, a planet whose valuable mineral deposits are being extracted by human miners. At first, the miners believe a murderous monster is attacking them because workers die and tunnels are damaged. Kirk and Spock eventually discover that the creature is protecting its eggs, which the miners have unknowingly destroyed or endangered.
Spock’s mind meld reveals that the Horta is the last surviving adult of its generation. Its species renews itself roughly every 50,000 years, with one adult remaining behind to guard the next generation of silicon-nodule eggs. Dr. McCoy saves the wounded creature with a silicon-based cement, allowing the Enterprise crew and the miners to understand one another rather than destroy the Horta.
The episode first aired on March 9, 1967, and is remembered for turning an apparent monster story into a lesson about misunderstanding another intelligent species.