Extremely dangerous elementals that could retrieve and manipulate information in the thoughts of living creatures. Wild forms were completely wiped out during the Terraforming Era, but fragments of them are still in use as Service Spirits.
Colloquially called "Brain Lickers."

Slug-like

as service spirit: 5-6 inches

High: wild types categorized as calamity class at minimum

"Chewing" or "licking" surface thoughts

Attempts to alter the motivations of attackers or disorient them by consuming their short-term memory

Anywhere with a self-sustaining population of sentient beings

Mainly solitary - too many individuals in one place will starve each other out

Continued exposure of living individuals to a Psychic elemental's feeding will leave "saliva" remnants within brain tissue. These coagulate into eggs that develop into polyps and eventually hatch out of the host brain.

None - not capable of much movement

Surface thoughts and memories of living creatures

Sea slugs, leeches, eels

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Continued exposure of living individuals to a Psychic elemental's feeding will leave "saliva" remnants within brain tissue. These coagulate into eggs that develop into polyps and eventually hatch out of the host brain.