But it's been said that Mata Nui island was formed by Great Spirit Robot as a camouflage? And we can't tell if Aqua Magna, being the shard of Spherus Magna, even had means to have volcanic activity.
And I understand your point, I am talking about some very advanced nanotech that we don't have concept of as of yet. The Great Beings have created Matoran Universe using just Protodermis, after all.
The Lightstones, as I theorize it, work only because Karda Nui works, spreading the Light energy all across the Matoran Universe The caves around it are supposedly littered with huge Lightstone crystals. It has nothing to do with actual quartz fracturing. When Onu-Matoran dug up a lightstone cave in MNOG, the lighstones inside were already lit.
That actually brings another interesting question: was GSR programmed to not only create an island on its face, but actually fill it with everything needed for survival, including Lightstones? Too many questions, especially for Greg Farshtey - or us - to answer.
But I digress. As I've said before, everything in Matoran Universe is, supposedly, Protodermis, unless it's not (there might as well be a form of Protodermis that is similar to magnesium, enabling the Protosteel production).
Protodermis is weird lol.
EDIT: Also, we do not actually know how long the Lightstones can last. Maybe they glow glow all the time! And I don't think fractured quartz actually can glow indefinitely. Or can it?