A knowledge crystal was a little larger than Toa Nuju's hand. If tossed onto the ground of Ko-Metru, a new Knowledge Tower would start to grow rapidly from where it landed. The new tower would grow to full height in mere seconds.1
Knowledge crystals about the size of a Matoran's hand were used to grow new Knowledge Towers. They were thrown into special cradles located at different places in Ko-Metru, from which they grew at a rapid pace until a new tower stood alongside the old ones.2
Knowledge Towers were not built, but grown. Special knowledge crystals were thrown into cradles throughout Ko-Metru, from which the towers grew at a rapid pace.3
The impact crystal launcher was a Xian weapon that used knowledge crystals as projectiles. It fired knowledge crystals through a thin film of liquid protodermis. When a knowledge crystal embedded itself in or near a target, a miniature Knowledge Tower grew around it, immobilizing the enemy. By varying the thickness of the liquid protodermis film on the end, it was possible to change the duration of time between the firing of the crystal and its formation into a Knowledge Tower.4
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.5, 6, 7, 8, 9 See memory crystal.