That was a convoluted and arcane script. It had been abandoned by the natives, thus, no trace of the ancient writings of the natives could be found in the flesh and blood civilization or at the base. Only occasionally could one glimpse these characters in the murals of secret rooms.
It seems in retrospect that the natives, having mastered this efficient method of consciousness communication, could understand each other without speaking. Speech was no longer necessary, and information could be stored in biological computers, rendering writing unnecessary too.
The combination of these factors caused language to lapse into a bygone relic within the flesh and blood civilization, only manifesting on the murals.
The natives looked back at their veins holding the skulls, and after a little selection, handed one of the skulls to a human-shaped whistle beast to eat.
It was as if a tree was inviting a passing traveler to feast on its fruit.
