|YOU'VE FORGOTTEN YOUR PURPOSE!
It has a strange biology, seemingly involving a unique and interesting internal ecosystem. The creatures within this monster appear to exist independently from the creature's own biology, as Jack and Ashi kill several without any apparent effect, and one creature appears to be feeding on other creatures within the beast's body, as opposed to working towards a common cause. It is also possible that the creatures are not unique to the beast, but have simply been swallowed by it and survived in the same way Jack and Ashi did.
It appears to be able to travel through earth and water seamlessly, with no obvious weakness to cold or heat as it first appears in a snowy area, and then in what appears to be a tropical ocean. It resembles a whale in many ways, emerging from the ground from the ground with its mouth wide similar to how whales feed on fish, and possessing a blowhole.
It seems to be either pretty terrible at hunting - it only manages to swallow Jack and Ashi in the entire width of its mouth - or to not be carnivorous. Its digestive system seems similarly ineffective, with life forms being able to survive by falling through one of many conveniently placed holes. It is possible the many other life forms contained within its body indicate other failures to consume its prey. Despite how far Jack and Ashi traverse through the creature's anatomy, no inorganic material is seen once they are swallowed. It is likely that the creature is able to sustain itself on rock and similar geological material (which would account for its lack of appearance; it would be destroyed in the creature's digestive process).