Null fragments. Oh, wow...
that takes me back.
Null fragments are used to craft a sequel to the
Null-A series. My copy is pretty old, I think it was an Ace Double with some lurid story about the Love-Starved Water Spouts of Zurg-1 on the other side.
Anyhow, it has some interesting parts of the Gaia storyline...the robot revolt, the origins of the water-loving Anchor Bugs (oddly enough, they come from a
dry planet), and portions of a now-lost Gnomic text that discusses the Old Gods (do not read this section aloud!!).
The book is well worth crafting if you can obtain enough fragments (233, I think).