Not all organisms feed on sound as the Race does. Many organisms must take their sustenance from other organisms, a fact that may occasionally baffle a city-dweller. Some of these organisms are quite capable of quickly killing and devouring a person before he can even utter a word. These predators, while deadly, are usually little more than a nuisance. Even though the Race may fight one another with word and song, they are still fully capable of creating bows and spears.
However, some times a creature may emerge from the tunnels, far greater than anything most will ever see. Giant creatures nearly as large as the tunnels themselves lumber through all that block their way, devouring all in their path. With many mouths and many ears, these great leviathans are seemingly impervious to all the Race can muster. More than one unlucky civilisation has been brought to ruin by the appearance of even a single creature. In desperation, some even worship the monsters, believing them to be gods or demons. Usually, their prayers go unheeded and are soon consumed.
Devastating and implacable, these leviathans in fact tend to live near the planet's core, rarely straying from their territories. What causes their great migrations is a mystery to the Race and most have concocted a myth or two to explain their rampages. In truth, the creatures migrate as part of their reproductive cycle. When food is rich, a leviathan will go into pregnancy, soon nurturing a tiny juvenile within it. Now needing food for both it and its child, the leviathan will emerge from the depths and devour all it can find. Interestingly, those consumed by the creature pass on their genes to the offspring. In this way, the asexual leviathans are able to ensure sufficient genetic variability in their child. In some cases, the resulting offspring may seem more like an individual of the Race than a leviathan. If it is able to survive its mother, the individual could possibly integrate into society. Supposing that the runt can reproduce, its descendants usually appear to be somewhat larger member of the Race. Within each of these descendants is enough genetic information to stimulate extreme growth if the immediate vicinity has enough food (i.e, a decently sized city). This growth will eventually result in the individual becoming another leviathan. Interestingly, leviathans created this way are just as non-intelligent as any other leviathan.