Congruent-Enigmatic scale

Enigmatics is a Covenant (originally Forerunner) classification describing sapient beings which diverge considerably from the cognitive and physiological baseline defined by the Covenant's ruling species. It is analogous to, though more specific than, the human scientific concept of xenosophonts.

Species like humans, San'Shyuum, Sangheili, Unggoy, Jiralhanae and Kig-Yar occupy a relatively narrow portion of the spectrum of sapient life. While their exact cognitive processes and median levels of intelligence vary, these differences do not pose considerable obstacles to everyday interaction. All have the capacity to grasp the same concepts, to share similar values, and have a roughly analogous capacity for object manipulation; likewise, all use vocal utterances as their primary means of communication and are capable of speaking the same languages, even if imperfectly at times. Enigmatics are species which, while demonstrably intelligent, sharply deviate from one or more of these commonalities. They may occupy a native biome that largely excludes them from everyday interaction, such as the Xar-Shaa. They may think much faster or slower than most other species, or in ways so different from other species that make interaction with them a challenge. Some may be entirely incapable of grasping concepts many species regard as the building blocks of civilization, such as language, religion or technology. Others exhibit clearly alien forms of cognition, such as eusocial hive-minds (e.g. the Yanme'e) or colonial gestalt intelligences (e.g. the Lekgolo).