Last time I didn't need a fuel crystal. Do you mean hatching enzyme? The hatching thing doesn't do anything when I go up to it. It should have a hand or something when I look at it sorta like to pick up an item. And the sea emperor still won't move.
I've found it!
1. Open steam and go to your library
2. Right-click Subnautica then select properties
3. From there click local files and then Browse Local Files
4. Then select the folder named SNAppData
5. Go to the fo…