Kuviu: What is this?
You know a fair bit about what's in the Medium since you've spent so much time watching the clouds and talking to people who live here. But you've never heard about a shell around Skaia. Maybe there's something to this disappeared Skaia thing.
On the bright side, this is definitely a Clue! If you can figure out what and where the shell is, you're basically halfway to getting Skaia back where it's supposed to be!