Archetypes are colosal humanoid creations that were excavated from the Scub. They serve as the "skeletons" of all LFO's. The scientists at the Tresor research facility had determined that the archetype was moving through the use of trapar, and decided to design the LFO to use the popular sport of lifting to fully take advantage of this ability.
Since the archetypes are part of the scub, Eureka seems to have the ability to communicate with them. The Nirvash being the main example of this. As she always tells how the Nirvash "feels" when something is being done to or around it.
The Scub Corals only had one form of communication. They fuse with anything, borrowing their physical body, but allowing them to remain as being of energy, within the Scub coral. The humans being scared of fusing and the Scubs not knowing they were being too aggressive, ended up with the humans leaving Earth and going to another planet. The Scubs were left with no intelligent beings to communicate with, so they created their own. They created thousands of archetypes in an attempt to recreate humans so they could communicate with them somehow. The only problem was that the humans had all left. When they the humans finally returned to Earth, all of the archetypes had already died, and the Scubs created lady Sakuya and Eureka in an attempt to communicate. The archetypes were failed prototypes of humans in an attempt to communicate with them.