Kaiju

Kaiju are the ultimate lifeforms and the final stage of evolution through the great amniotic fluid. They are completely unique organisms that have grown immensely in size and power, more so than their cryptid counterparts. Greater amniotic fluid exposure is required to evolve a cryptid into a kaiju, provided they are capable of making the evolutionary leap. All kaiju evolve from cryptids and are classified as such, but the reverse is not seen as true. All kaiju are cryptids, but cryptids are not kaiju. Those that can evolve into a unique species of their own separate from their original species, becoming the first - and often also the last - of their kind.

The exact logistics behind how and why kaiju evolve into their forms is unknown. The great amniotic fluid amplifies base genetic traits both dormant and dominant in order to protect the specimen and elevate it as the apex of its environment. Even birth defects and abnormalities that would often prove fatal or hinder survival become viable advantages in the wild. Avatism, convergent evolution, divergence from old lineages, gigantism, and various others are all part of the evolutionary process. It is predominantly believed to be an entirely random process, but more radical cryptozoologists and cryptogeneticists propose the idea that of some degree of intelligent design from a semi-sentient amniotic fluid. This claim is highly dubious and hotly debated in the cryptozoological community.

Kaiju are the largest lifeforms to have ever lived on planet Earth, only being rivaled by the blue whale. Though kaiju are naturally large, their size was often proportional to the potential predators around them. Land-dwelling kaiju were typically even in terms of height, easily outsizing any terrestrial land predators like dinosaurs. Aquatic kaiju - however - was larger and varied in greater sizes than their land-dwelling counterparts did in order to outgrow potential ancient predators such as Megalodon, Kronosaurus, or Livyatan. Kaiju retain their large size in the modern day even with the lack of land or sea predators. They are also highly resistant to human weaponry, and most of them are immortal because of their advanced regenerative bodies.

Most kaiju lack sentience, and those that do possess incredibly limited intelligence on par with apes, unable to speak or articulate themselves. However, they do appear to possess limited levels of judgment, scrutiny, and varying degrees of self-awareness and thought.

Kaiju have been incredibly prevalent throughout human history, having shaped all culture, religion, folklore, mythology. The majority of kaiju have been hunted to extinction or killed in conflicts with each other, while others have been in hibernation. All that remains of their existence has been drastically altered, changed, mistranslated, or ultimately lost because of the constantly shifting human cultures.