That one? It's the power source for it's strange bullet replication technology. Science fiction! It'll have glowly bits and not just be flat roundness later on.
Is the thing you're trying to replicate a single watertight surface or made of multiple pieces? If it's the latter, you should probably make the model out of multiple pieces
If you share the model in FBX or OBJ format, others might help by examining it for errors. (to upload a model, put it into a ZIP file, then drag-and-drop into your reply)
Thanks, it worked in the viewer! Is there anyway of getting the skycube thing to display to the same settings as the editor? It doesn't seem to replicate.