Memory crystals were objects used in Knowledge Towers to store information. Data could be recorded in the crystal by means of physical contact with a scholar, but the operation needed to be triggered by the will of that scholar.1
Notes
Ko-Metru was dominated by enormously tall knowledge and memory crystals. Nuju's task of guarding the knowledge and memory crystals of Metru Nui was a lonely one.2
Matoro once proposed a theory that, at one point, some frost beetles consumed memory crystals and somehow absorbed the knowledge inside them, passing it on to others through a sort of hive-mind and thus increasing the intelligence of the entire species.3
Knowledge crystals and memory crystals were apparently similar but distinct objects. Both memory crystals and knowledge crystals were able to store information and were used to grow Knowledge Towers.4, 5, 6, 7, 8 See knowledge crystal.