Kappa

Anthropomorphic alt-timeline ankylosaur/chelonian-derived semi-sapient. This amphibious interdimensional ambush predator can instinctively phase-shift between probabilistic worldlines in opportunistic pursuit of prey, but can only emerge in a freestanding volume of orthodox liquid water greater than 8.5K cubic liters and possessing a salinity of less than 1K parts per million (in dissolved chemical salts). The reason behind these narrow physical parameters for manifestation is currently unknown, but may be a transcosmic selection factor limiting resource depletion within aquatic ecosystems.

On dry land, the "dish" of local water atop the creature's head is necessary to synchronize its Kirlian field with the native ion concentration of its current biocosm. A reflexive "bowing" response towards challenging signal behavior from conspecifics thus renders the Kappa vulnerable to potential predators (or threatened prey) able to trigger this instinctual reaction outside its native continuum, resulting in neurological disruption and likely probabilistic collapse back to its world of origin.