If you're looking for an easy way to create some space rocks or other geological formations, try this generator by 3D Artist Deepak Kushwaha, which lets you quickly make asteroids by drawing curves. The rocks are easy to texture too:
Asteroid Generator
Asteroid Generator
Asteroid Generator
Grab Asteroid Generator here. You might also be interested in our recent interview with Adam Swaab, who shared the inspiration and creative process behind his nebula experiments crafted using Houdini:
Grab 0x384c0's project files and check out the tutorials to learn how to do something similar: