- piqlfilm - nano qr on 35mm = 500+ yrs https://cld.bz/users/user-WmA6B3j/Piql-Introduction/8/
- memory crystals = gazillion yrs https://en.wikipedia.org/wiki/5D_optical_data_storage?wprov=sfla1
- https://en.wikipedia.org/wiki/Holographic_Versatile_Disc?wprov=sfla1
- https://en.wikipedia.org/wiki/5D_DVD?wprov=sfla1
- https://en.wikipedia.org/wiki/Hyper_CD-ROM?wprov=sfla1
- Hard-core data preservation: The best media and methods for archiving your data
- Data storage lifespans: How long will media really last?
M-disc is the best choice.