Subterranean Hollows

Our archaeologists have unearthed enough sections of the tube-like, swirling hollows on … to conclude that they are the fossilized remains of an enormous arthropod! This alien creature, carbon-dated to having lived some ten million years ago, tunneled slowly through the crust of the planet, like a burrowing millipede of incredible proportions.

Even more remarkably, many of the components embedded in the magnificent creature's fossilized remains appear to be of artificial origin. These imprints, found primarily within the main body segment of the creature, look like habitations built by smaller, tool-using aliens.

Further archaeological efforts are warranted.

Extensive excavation of the fossilized imprints within the giant subterranean arthropod remains on … have confirmed these are indeed the remnants of a city! Populated by hundreds of thousands of meter-tall, tool-using creatures, this city was constructed within the very bowels of the gigantic arthropod. It is unknown how these creatures found their way inside of this subterranean giant, but their pre-Bronze Age society seemed to flourish for thousands of years within its digestive tract.

Further study is required if we wish for further insight into this society's history and downfall -- and perhaps glean more about the death of their host.

After painstaking analysis of a large number of fossils and a few miraculous finds of early writing, our archaeologists have reached a conclusion regarding the relationship between the primitive civilization on …, and the gigantic arthropod that was home to them.

While the city-dwellers were largely resistant to the intestinal fluids of their arthropoid host, constant exposure to the still mildly chemically corrosive gases of the host's digestive tract vastly shortened their lifespans. Owing to their discovery of medicine and the scientific process, the citizens became aware they were in fact living within the digestive chamber of a much larger creature. The citizens then launched a magnificent war, arming every member of the city in an attempt to destroy the creature.

But it was all for naught. The turmoil in the arthropod's lower gut led to severe peristalsis, resulting in the entire civilization of tiny city-dwellers being regurgitated up into the arthropod's stomach. Subsequently, the entire populace was promptly dissolved by their host's virulent stomach acids.

The creature itself perished millennia later, from simple old age.