In the short story "In the House of the Worm", the main character gets to see a panel (sort of mural) that depicts
an intricate, labored depiction of sword-swinging grouns battling a giant whose eyes were thetas and whose fingers were worms. [The main character] had to look hard and long to make sense of the scene, however; as with the tapestries of the yaga-la-hai, here too the colors were dim and fading, and rust had eaten black, flaking holes in some of the panels.
As opposed to the main character, I couldn't make much sense of the scene. I recognized though, the constant references to
the theta sign, the one employed by the Federal Empire's Ecological Engineering Corps in Tuf Voyaging, another of Martin's tales (or series of tales).
I know that George R.R. Martin creates highly detailed worlds which are consistent for many of his different stories. Unfortunately, I wasn't able to gather much about the relationship between the aforementioned sigil, the people who used it, and the different species living in In the House of the Worm.
I was hoping somebody could help me to put some of the pieces of that puzzle together. What is the background history for the events depicted in In the House of the Worm, in relation to the scene depicted in that panel and the