Blender is excellent for creating any scene, but Fantasy and SciFi scenes are best suited as Blender offers you the creative freedom to create anything you like. 

When creating SciFi Scenes, I have often missed an easy way to bring in rocks, or rock formations, that make the scene scream "ALIEN"!
I´m not referring to the movie franchise, but my rocks are heavily influenced by the works of H.G. Giger and the Lovecraft universe.

NOTE: 

• The assets come without texture, so you can integrate them seamlessly into your specific scene
• The assets are Ultra-High-Poly - depending on your system, you may experience some lag
• I have created all these assets by using various sculpting methods and custom brushes

PS. These assets work very well with True-Vfx addon "True Terrain" ;)

PPS. If you watch the YT Video on how I create an Alien Landscape you get an additional Alien Rock (with matching icon for your library). 

ENJOY!