Gran and the cat merchant continued exploring, collecting stone-eating bug shell residue. The cat merchant explained that ground into powder, it could be made into an abrasive compound finer than sandpaper—something dwarf smiths would probably love. As they descended, the sound of water drew closer, the air grew damper, and faintly blue-glowing moss began appearing on the walls.
They reached a natural rotunda. A crack split open its center, carrying a black underground river. But it wasn't the underground river that made the cat merchant stop. Embedded in the walls of the rotunda was a mineral he'd never seen before. The minerals were shaped like frozen droplets, varying in size, and their colors shifted from deep blue to pale gold to transparent, as if they were breathing.
The cat merchant approached the wall and shone his torch on the minerals, only to discover that their color changes accelerated. He reached out and felt a faint pulse, like a heartbeat, but much slower. To his astonishment, the minerals were alive—not "alive" in the sense of a living ore vein, but truly breathing.
Gran stood behind him, watching the cat merchant's trembling back. The fur on his two tails had puffed up, and the tails beneath his cloak had slipped free as well, spreading like an opened fan. The cat merchant asked Gran whether, after mining here for so many years, they'd known this thing was here. Gran shook his head and said they'd never gone this deep.
The cat merchant stared at the breathing minerals, the light in his eyes brighter than the torch. He wanted to touch them, but in the end he withdrew his hand and took a deep breath. The tails beneath his cloak slowly drew back in, leaving only the two outside, still trembling faintly.
"Business first," the cat merchant said hoarsely, his gaze sweeping across the rotunda before settling on the rocks along the underground river's edge. A layer of gray-green Ghostspring Moss grew over the rocks, its edges tinged faintly black, as if it had absorbed something it shouldn't have.
He crouched down, took oilcloth and a scraping knife from his leather satchel, and carefully collected the moss. His movements were slow and gentle, as though peeling away a layer of brittle skin. "This stuff grows beside water where something has died." He explained as he worked, his tone returning to normal. "See this ring of black along the edge? It means a living thing once died in the water here. The longer it's been dead, the thicker the moss grows. This patch... at least a few decades old."
Gran didn't ask what had died in the water. Deep underground, whatever died in an underground river was unlikely to be an answer anyone would find reassuring.
The cat merchant gathered enough for their needs, wrapped it carefully in oilcloth, and put it in his leather satchel. He stood, then looked once more at the breathing minerals in the wall. He stared for a long time.
He pulled his little notebook from the leather satchel, flipped to a fresh page, and quickly sketched the minerals—their shapes, distribution, color-change patterns, and pulse frequency. Then he wrote a single line:
"Unknown living mineral. Non-derivative, possibly an independent life-form. Must return."
He closed the notebook and slipped it back into the leather satchel. "Let's go," he said to Gran, his tone light. "Your granddaughter is still waiting."
As they headed back, the cat merchant glanced over his shoulder. The minerals in the rotunda were still breathing, their color slowly shifting from transparent to deep blue, as though seeing them off.