The hollows of Vasca do not hold still. Every six hours, the tide pushes through cracks in the basin floor, filling the lower chambers with warm, mineral-heavy water. Creatures adapted to this rhythm do not swim — they wait. Anchored to porous walls, they filter what the flood brings: spores, dissolved salts, the shed skins of things that passed through seasons ago. Biologists who first mapped these chambers noted an unusual density of bioluminescent organisms clustered near the ceiling — the one surface the tide never fully reaches. Whether this is refuge or ritual, no one has yet determined.