The gristo is an eel and communicates as such.

Gristo eels come in a wide variety of muddy colours. They look much like any other eel apart from the extra eyes, whose placement on the head can vary somewhat. Every swamp fisherman knows someone who pulled in an eel with an eye inside its mouth or some such place. More typically, a gristo's eyes will appear as two sets of two, with the fifth eye on the forehead.

The gristo eel is native to the saltwater swamps of the Bayou Garramarisma and the seaward fringes of the gigantic Iuk'u Delta. Somehow or other, it can also be found in the grimy inlets of Black Bay near Cerak At'Thul, thousands of miles away.

The gristo dies very slowly, a piece at a time, in predictable ways. It's easy to damage the gristo enough that it stops moving around, but it'll keep twitching until it rots, unless thoroughly cooked. It's not uncommon for racks of drying gristo flesh to shiver and clatter. The eyes are the last to go: they often blink and watch moving things for weeks after decapitation. Chunks of still-moving gristo flesh make good fishing bait and can last for hours.

There's not much of interest in the history of the gristo eels. They've featured as a curio in Alliria's bazaars for decades and attracted relatively little attention. Crossroad Mire, a fringe-magician village and school in the bayou, stocks gristo parts in quantity for research and barter purposes.

The gristo is well known in its native regions as a catch not worth the effort. It's given rise to plenty of tall tales, even some superstitions. There's a common, almost certainly apocryphal story of a man eaten alive by the gristo he just cooked and ate for dinner.

Alchemists and users of mimicry may prize the gristo, but its usefulness is subjective, poorly explored, and highly situational. Magicians may know of foolish colleagues who aimed for immortality but wound up taking a week to die.

A drink called a Jealous Lover involves a pickled gristo head whose eyes still move. The drink is a well-known novelty in The Shallows and parts of eastern Liadain.

• Gristo samples at Crossroad Mire
• A gristo head in a drink
• Gristo used in a potion