Bonecracker (artwork by Yuujinner)
Species: T. pentops (“five-eyed long jaw")
Temporal range: unknown to recent (??? - present)
If the cave clicker is the so-called monkey analogue of the Akamanucha cave system, then the bonecracker is the lion looking for a bite-sized meal to tide him over to his next feast.Â
Typically approaching the physical dimensions of a polar bear but weighing less than half as much, the largest members of this species would be able to contend with the theropods who stalk the surface above, reaching nearly 20 feet in length and over 700 pounds. In fact, this animal is so large for an invertebrate, breaking the previously understood upper limit for arthropod body size several times over, that it has actually been suggested by some researchers that something equivalent to abyssal gigantism may be the reason for why it grows so big, though the more conspiracy-inclined suggest genetic manipulation from high lifeforms is at play. As the cave is known to sit near volcanic fissures and is therefore able to support such a large and vibrant ecosystem, it has been suggested that it may also be a product of highly nutrient-dense water and prey animals allowing this animal to grow to a much larger size than should otherwise be plausible. However, its disproportionately large jaws do not seem to match the size of its prey, which are rarely larger than a sheep, suggesting that it may have been specialized to hunt an especially large cave animal which has since gone extinct.
Whatever the case, this creature’s anatomy is so confusing, being jokingly described by one of the scientists who retrieved the holotype specimen as, “the result of a one-night stand between an entelodont and a crustacean of some sort”. So baffling was this animal, in fact, that initially, scientists weren’t able to figure out what specific clade of arthropods it belonged to (if it was even an arthropod to begin with). However, genetic analyses and studies on its morphology finally revealed it to be a stem-group arthropod nested amongst the paraphyletic dinocaridids, being particularly closely-related to an inconspicuous opabiniid found on the surface in coastal tidal ecosystems known as the *elephant prawn*, with which it shares a most recent common ancestor over 450 million years ago. This solves one question but still leaves many left unanswered, such as how the jaw structure came to be and, more glaringly, how it, along with several other species descended from ocean-dwelling clades, ended up in the caverns. The prevailing theory is that the caverns were once connected to the oceans via an inland sea, and as the inland sea dried up, many of the creatures became trapped in subterranean lakes and rivers within the caverns, eventually moving onto land and adapting to life within the caves. However, as no transitional species which would link the features seen in the bonecracker to its less derived cousins has been found, this is difficult to verify.
With a jet black, iridescent body, white setae, and tail fins which shine bright red and violet spotted patterns when in UV light, this creature is as beautiful as it is frightening, a pinnacle of the cave’s deceptive beauty. Though larger predators exist in the Akamanucha cave system, it appears that none are willing to directly challenge this creature, a beast clearly feared by both predator and prey alike, and from what has been confirmed by both cameras and direct observations, other large predators either vacate the upper levels of the cave at night entirely to avoid this animal or hide away wherever they can as its makes its nightly vertical migrations up to the upper levels of the cave system in search of food, the means by which it times these migrations still completely unknown. Indeed, this animal appears to be the apex predator of its cavernous ecosystem, unafraid to bully similarly-sized predators out of kills. In fact, it won’t even tolerate its own kind under the best of circumstances, and when two bonecrackers cross paths, the ensuing scuffle often ends in the death of one or both parties, its characteristic rasping shrieks and “roars” being a way of notifying other members of its species of its position and not to come near. In fact, its aggression towards other species has made it challenging for researchers to even get close enough to properly study this animal, and it has been implicated in many attacks on researchers, including at least one death where it managed to decapitate one unfortunate researcher who had stumbled to the ground trying to flee from the animal. A sight-based predator, it can see a wide range of color despite the rather dark and monochromatic depths it dwells in during the day, with an exceptional ability to see UV light. This ability allows it to spot prey from far away and to better distinguish its prey from the faint bioluminescent hues given off by the fungi of the cave. Because its sight is so well-developed, most researchers venturing into the bowels of the cave keep flares on them in the event that they encounter one of these creatures. By contrast, however, its hearing and sense of smell are rather rudimentary if not highly underdeveloped.Â
Despite its social and dietary behavior being well-documented for a creature which is relatively understudied, next to nothing is known about its reproductive biology. However, most evidence points to internal fertilization and an ovoviviparous nature, rearing only a handful of young at a given time to ensure the best chances of their survival. Remarkably for a creature of their size, they are believed to have incredibly short lifespans, likely living no more than 20 years. Their population size is likewise believed to be rather small, possibly no more than a few thousand (at most) at a given time. Much like the cave-clickers they seemingly prey upon, none of the specimens captured and brought to the surface survived long after arriving to the surface, dying within days of surfacing.Â
While there are no unambiguous interactions between humans and bonecrackers prior to the mid-21st century AD, and these creatures appear to be entirely absent from cave paintings found in other areas of the caves, there is a fringe theory amongst some scientists that these animals inspired traditional depictions of demons in the native folklore of the human inhabitants, as the underworld in the folklore of the Xenogaean people (the inhabitants of the country of Xenogaea, which occupies the archipelago) is described as being remarkably similar to the surface world in many aspects, having its own native flora and fauna as well as intelligent species of varying moral dispositions. However, they considered the underworld creatures to be twisted reflections of that on the surface, nightmarish creatures which were unrecognizable to the surface-dwelling world. As highlighted previously, however, since there are no confirmed interactions between the two species in antiquity, this cannot be proven beyond a shadow of a doubt. However, seismic equipment has picked up readings of possible manmade structures at the very bottom of the cave, and trackers would seem to indicate that bonecrackers congregate near these in surprisingly large numbers, more than would otherwise be expected for such a territorial animal. Some suggest these creatures are guarding something, perhaps something which humanity is not yet supposed to see, while others believe that they simply use these structures as a place to shelter. Regardless, these creatures appear to guard many secrets, and not just the ones related to their own biology…
