Little is known for certain about the Kerguelen Zorn. My belief is that it is a human mutation induced by viral infection.
The creature in question was clearly human to begin with. Evidence suggests that the transformation from man to zorn can take up to two weeks. In some cases, however, it occurs in a single day.
The infected person's skin becomes dark magenta -- as if it has been boiled. The head and torso become filled with fluid. The face and neck become so distended, they practically disappear.
Having become massively top-heavy, the organism inverts --- it drags its former head on the ground, and its legs stick straight up in the air. It appears that rigor mortis takes over in the legs... They become stiff, and much of their color drains away. The arms each split into two new limbs. Separation begins between the ulna and radius; one of the new limbs will have two fingers -- the other will have two fingers and a thumb.
The creature, now with four lower limbs, walks somewhat like a spider -- but dragging its slippery, sagging mass along on the floor. It is apparently blind, and finds its way by frantic, groping touch. In a low hallway, the dead legs may bump and drag above it -- almost giving the impression that the thing is walking on the ceiling.
The zorn-producing virus is highly contagious -- likely being transmitted by physical contact. My suspicion is that the virus originates from the submerged microcontinent beneath the Kerguelen Archipelago (AKA "Desolation Island"), which sunk into the ocean some 20 million years ago. I believe that an illegal oil-drilling operation recently unearthed the disease.
I have attempted to "quarantine" the virus. I hope and pray that no Kerguelen Zorns have survived.