There are tons of crappy Game of Thrones fan theories out there, but one theory, about where dragonglass really comes from, is crappy for an entirely different reason. Given its seeming importance to the overall story of A Song of Ice and Fire, it should be no surprise that fan theories about dragonglass are as abundant on the Internet as the substance itself is on Dragonstone. But few can compare to the toilet-themed theorizing of one individual on Reddit. To The_Others_Take_Ya, dragonglass isn’t some magical and mysterious rock that somehow kills White Walkers — it’s dragon poop.
While the theory might sound ridiculous at first, it should be noted that George R. R. Martin is known to embrace all aspects of life in his fantasy worlds, even the less-than-glamorous bits. Dragons eat, and therefore, they likely excrete waste. From that point, there’s actually a surprising amount of evidence that not only is dragon poop present in the story, but it’s vitally important to its conclusion.
Let’s be clear — in a George R. R. Martin fantasy world, nothing is off limits. This is the author, after all, who dedicated an entire chapter to Daenerys Targaryen, Breaker of Chains and Mother of Dragons, experiencing diarrhea out in the wilderness. GRRM likes to explore every aspect of life in his novels, from the violent and extreme to the routine and mundane.
It stands to reason, then, that Daenerys’s dragons, and all other historical A Song of Ice and Fire dragons, must poop. They eat, and therefore they need to excrete waste in some way. It would not be out of the ordinary in the slightest for George R. R. Martin to make this a part of his story.
The basics of the “dragonglass=dragon poop” theory, eloquently created and explained by Reddit user The_Others_Take_Ya, is that dragons eat dirt and poop glass. It has a lot to do with firewyrms, rock-tunneling beasties George R. R. Martin has described as related to dragons in the ASOIAF extended material.
The firewyrms are known to dig massive tunnels through rock, and it appears dragons have this ability, too, based on the escapades of Daenerys’s dragons while in captivity. It stands to reason that a lot of dirt, including silica or quartz sand, would be ingested while tunneling, which could result in a glassy substance getting excreted by the creatures due to their intense internal heat. The result could be described as dragons pooping molten glass, which would then harden into dragonglass.
In both Game of Thrones and A Song of Ice and Fire, Daenerys chooses to chain her two smaller dragons, Rhaegal and Viserion, in the Great Pyramid of Meereen. The books go into much greater detail about this captivity, included the fact Viserion eventually broke out of the chains and began tunneling into the foundation of the pyramid, for the speculated purposes of sleeping in there.
Or, as Reddit user The_Others_Take_Ya argues, perhaps Viserion dug the tunnel as somewhere to go to the bathroom. This would set the precedent that dragons dig tunnels, in part, to give them somewhere to dump their waste, which would make sense given the other known set of dragon tunnels in the story.
Other than the ones dug by Daenerys’s dragons, the only other set of known dragon tunnels in A Song of Ice and Fire are the massive system of tunnels underneath Dragonstone. According to Westerosi history, dozens of dragons made Dragonstone their home in the decades before and after Aegon’s Conquest, and they certainly did their share of tunnel-digging. Again, if dragons do poop (and why wouldn’t they), there’s almost no way those tunnels aren’t full of the stuff. So, why isn’t it everywhere? Well, maybe it is.