Monolith
From Kerbal Space Program Wiki
**Spoilers**
Monoliths are easter eggs that can be found in several places throughout the Kerbal solar system. They are most likely a reference to the Monoliths from Arthur C. Clarke's Space Odyssey series of novels and film. They currently have no known function.
For a list of locations of all discovered monoliths click here and select 'anomalies' from the menu in the top right corner.