Researchers at the University of Southampton in the UK successfully stored the entirety of the human genome sequence onto an indestructible 5D optical memory crystal no bigger than a penny. The indestructibility claims are no joke since the discs can withstand temperatures up to 1,000°C, cosmic radiation, and even direct impact forces of 10 tons per cm2.
So I’m imagining them as a legend based on unverified lore, conjecture, and conflicting information with no real evidence of them ever existing and I’m having a difficult time seeing where the value lies in that.