How many ghosts are there, and what do they say?

Question

In the graveyard levels I encountered multiple ghosts.

You can see them when the lightning flashes. Pressing "B" will cause them to say something.

How many are there, and what is the transcript of what they say? Is there any known relationship between what they say and a puzzle or easter egg?

Answer 1

There are four ghosts and they're unconnected to the puzzles and Easter eggs.

• In the skull room: "Afterlife / Outerspace / Afterspace / Outerlife."
• In the "dots to dots" room that leads to the mausoleum: "Don't believe the hypercube."
• In the room atop the prior one: "Because you can't see something, doesn't mean it's not there."
• In the golden cube return warp (farthest away): "Owls creep me out... / But I forget why..."