One of the Gi, a race of alien beings, named Normus.
A pyramid-shaped being (actually a three-sided pyramid, a tetrahedron). Looks pretty much like a pile of rocks until you realize he has opened one of his four eyes and is staring at you. No visible limbs — until he extends one of his apexes to create a hand or a foot.
Spends his time rolling around the Island from one of 13 different pyramidal rock formations to the next, according to a predetermined and complicated pattern known only to himself.
His backstory is revealed as the solution of a puzzle involving 13 different places on the Island map.
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This narrator is responsible for the characters: