The convex gargoyle lens is old, having been crafted by Naxatilor and Lor-wis-lem many centuries ago to draw the Codex from the Void. At the time of the False Prophet it was broken and resided in the museum. The Avatar had to get Lor-wis-lem to repair it, so that the lenses could be used to end he war between gargoyles and humans.
Both lenses were used together with the Vortex Cube, the eight moonstones, and the Eternal Flames of Infinity and Singularity to return the Codex to the Void. Human or gargoyle can still read the Codex at the shrine with both lenses.
By the time of Ultima VII however, they were moved to the museum. In Forge of Virtue it was revealed that the lenses can draw objects back and forth from the Void, such as done with the Talisman of Infinity and the Dark Core.
In Ultima IX, the lenses were used once again, but this time to decyper the Codex.
- In Ultima VI the Avatar is instructed to place the Concave and Convex Lenses midway between the Codex and the two Eternal Flames. This was meant to focus the light of the flames upon the Codex. With real world physics, however, placing the two different lenses halfway between the lightsource and the object would not have worked as the game intended.
- The function of the lenses in Ultima IX was different, and the lenses were much smaller.