Fauna
The Tide-Marked Thalshark patrols the moon-pulled coasts of Originis as a sleek fusiform predator five meters long, its dorsal a deep blue-grey washing into a moon-pale belly via a clean lateral line of silvered tide-marks that brighten and dim with Pale Sister's phase. Dermal denticles lie fine as silk and turn the body almost frictionless; a touch leaves the hand smelling of cold metal. Five gill slits arc behind a wedge head whose obsidian eyes watch with the unblinking patience of deep water. Pectoral fins ride wide and stiff, the crescent caudal fin sweeps in slow economical beats, and a row of ampullae along the snout reads the chord-electricity of struggling prey. Inside the jaw, three replacing rows of serrated teeth glint with the planet's faint magnetic glow. The silvered tide-marks are not pigment but a layer of micro-scales that refract Pale Sister's light, so the shark seems to drag a ribbon of moon along the flank as it cruises the kelp shadow.
Thal song-priests harvest a single Tide-Marked tooth from a beached carcass to set in their chord-staves; the tooth hums in time with Pale Sister, marking the priest's voice as legitimate. Thal mothers warn children that the silvered tide-marks count the souls a Thalshark has taken, though biologists insist the marks are merely refractive scales reset every moon. No Thal will swim alone on a new-moon night when those marks go dark.
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