Chen Hao's fingers were still on the water droplet; the coolness had barely dissipated when the heat rushed back in from all directions. He withdrew his hand, shook the dampness from his fingertips, and the smell of burnt shoe soles still lingered in his nostrils.

“We can’t wait any longer,” he said. “Plants produce water too slowly; we can’t afford to wait.”

Nana leaned against the wall, the spot on her right arm where the water bag had been was already dry, and a thin layer of white frost had formed on the surface of her armor. She didn't move, but her voice came out: "Detection system restarted to 60%, short-range scan is possible."

“Then let’s sweep.” Chen Hao stood up, patted the dust off his pants, and said, “Let’s find something usable. Water, energy, anything that can sustain us will do.”

Susan put the vine sample from the sealed box into her backpack and checked the insulation on the pliers. Carl was removing another piece of wire, intending to add a second cooling circuit to his protective suit.

"Which way?" he asked.

“In areas with many cracks,” Nana said, “the geological structure indicates that there may be closed cavities inside the rock wall, where the probability of humidity and mineral enrichment is higher.”

Chen Hao grinned: "You mean the hole?"

"yes."

“Great, I’ve been wanting to crawl through a hole for a while now.” He lifted his foot and walked forward, his left shoe limping. “Since the shoes are ruined anyway, walking barefoot will save some insulation material.”

No one responded.

The four of them moved along the edge of the passage, avoiding the central high-temperature zone. Occasionally, molten slag remained on the ground, making a slight cracking sound when stepped on. The air grew increasingly stuffy, and their throats became dry with each breath.

After walking for less than ten minutes, Susan suddenly stopped.

“Over there.” She pointed to the right rock face, where several vines hung down, obscuring a narrow crevice. “There’s a breeze.”

Others gathered around.

The gap was only half a meter wide, hidden by layers of vines. Nana reached out and parted them, her metal fingers scraping against the plant's surface, making a rustling sound.

“The internal airflow is stable, the humidity is 78%, and the temperature is 11 degrees lower than the outside,” she said. “Moreover… there are faint energy signals.”

"Crystals?" Chen Hao's eyes lit up.

“Highly likely.” Nana nodded. “The preliminary assessment is that it is a non-metallic luminescent body with wavelengths concentrated in the blue-violet range of the visible light spectrum.”

“That’s it.” Carl lifted his toolbox up. “What we’re lacking is this kind of high-density energy source.”

"Let's go in and take a look." Susan had already pulled out the pliers and fastened them to her belt.

Nana went first, squeezing sideways through the gap. Her headlamp lit up, illuminating a sloping, downward-facing rock path. The ground was slippery, riddled with tiny grooves, as if it had been eroded by water for many years.

Chen Hao followed behind, his foot slipped, and he almost fell to his knees. He cursed and steadied himself by grabbing the rock face.

"This road is more slippery than a frying pan."

"Don't touch the wall." Nana turned around. "There are corrosive salt crystals on the surface."

"You should have said so earlier!" He quickly pulled his hand back, his palm already red.

"I'll tell you now."

Carl was the last to come in, panting as he unloaded and inspected his backpack. Susan walked at the back of the line, her gun not in hand, but her hand resting on the handle of the pliers.

The path widened as we walked along it, and after turning a corner, a wide-open space suddenly appeared before us.

A cave of moderate size appeared before them. Several clusters of luminous crystals hung from the ceiling like icicles, emitting a faint blue light. In the center of the ground was a small pool of water, its surface reflecting the light and shimmering slightly.

"Water!" Chen Hao rushed to the side, squatted down, and tried to scoop it up with his hands.

"No!" Nana grabbed him. "There are signs of marine life in the water."

He froze and looked down.

Something was definitely wrong with the water. Every few seconds, tiny ripples would spread out from the center, as if something was gently swaying underneath.

"It's not a fish, is it?" He withdrew his hand.

“No.” Nana scanned the crystal. “It’s an arthropod, not very big, semi-transparent, and communicates by sound waves. They gather around the base of the crystal.”

Everyone looked in the direction she pointed.

Deep within the cave, a large crystal grew from a crevice in the rock, its surface a deep, dark blue. Seven or eight creatures, each the size of a fingernail, lay upon it, their bodies trembling slightly and emitting an almost inaudible buzzing sound.

"Are they guarding it?" Susan asked in a low voice.

“Probably.” Karl stroked his chin. “This thing is very important to them.”

“We’re important too,” Chen Hao said. “Who will make the first move?”

“We can’t just take it by force,” Nana said. “Their sound frequencies can interfere with electronic devices. The scan was interrupted twice just now.”

“Then let’s find a way to shut them up.” Susan looked at Carl. “Didn’t you make a low-frequency pulse device?”

Karl paused for a moment: "That's for conducting heat."

“Make a change,” she said. “Could you make it emit reverse noise?”

He frowned in thought, his fingers rummaging through his toolbox for parts. "Let's try it. It'll take five minutes."

“I’ll buy some time.” Chen Hao stood up and tore a reflector off his protective suit. “I’ll play a trick.”

Five minutes later, Carl connected the modified wiring to the watch and pressed the switch.

A very low tremor came, like a muffled sound rising from the depths of the earth.

The creatures in the cave reacted immediately. They stopped trembling, curled up, and flailed their tentacles.

"It works!" Carl whispered. "They're in chaos!"

“Now.” Susan crouched down and approached the crystal, extending her pincers.

With a snap, a small piece of the crystal broke.

The swarm of creatures suddenly exploded, and two of them pounced on her, moving so fast that they were just shadows.

Chen Hao raised the reflector and waved it back and forth towards the light source above his head. The blue light danced and leaped on the cave walls like flashes of lightning.

The creatures were drawn to the light and shadow and turned toward him.

Susan took the opportunity to cut off another piece and quickly retreated.

“Three pieces are enough,” Nana said. “If we take any more, we’ll be in big trouble.”

"Retreat." Chen Hao threw the reflector on the ground and turned to run.

The four of them left the rocky path and returned to the platform outside the entrance. Chen Hao plopped down, his bare feet sinking into the cool stone, and hummed contentedly.

"Finally, something real." He panted. "Much better than my drop of condensation."

Susan opened the sealed bag and placed the three crystals inside. Blue light shone through the bag, making the edges of her gloves appear bluish.

"There's no surface corrosion," she said. "It's safe for now."

Carl took out the remaining materials and began assembling the insulated box. He used discarded battery casings as the lining, then wrapped it with an insulating layer, and finally sealed it.

"It can prevent energy from escaping." He patted the box. "It will last for at least a few hours."

The frost on Nana's right arm hadn't melted yet. She leaned against the rock wall, the system interface flashing.

“The data has been saved,” she said. “The original signal packet is intact.”

"Are you alright?" Chen Hao asked.

"I can manage." She paused, "It's just that my right arm joint is a little stiff."

"Don't end up unable to lift a gun." Susan glanced at her.

“I can still move,” Nana said, “just a little slower.”

Chen Hao looked up at the sky—if this place could even be considered a sky. The cracks in the ceiling still emitted a dark red light, like the bottom of a furnace that had been burning for a long time.

"What do we do next?" Carl asked.

"Let's figure out how to use this thing first." Chen Hao pointed to the insulated box. "We can't exactly use it as a nightlight, can we?"

“We need to analyze it,” Nana said, “but the conditions aren’t right now.”

“Then let’s find a place.” Susan put away the bag. “As long as I don’t have to step on the molten slag again.”

"I've lost all my shoes." Chen Hao looked down at his bare feet. "And you're still picking and choosing your path?"

“You can climb,” Carl laughed.

“Say one more word and I’ll sit on you.”

After resting for about ten minutes, the group regained some strength. Chen Hao stood up, wiggled his toes, and winced in pain.

"Let's go," he said. "Let's go back and get some sleep. Even though there's no bed."

The four packed up their gear and prepared to return to the main passage. Nana walked in front, her movements slower than before. Susan brought up the rear, holding a gun. Carl carried the insulated food container, walking cautiously.

Just as Nana reached the edge of the platform, she suddenly stopped.

"What's wrong?" Chen Hao bumped into her back.

“The signal has changed,” she said.

"What signal?"

“The crystal.” She raised her left hand and pointed to the insulated box. “It just… flickered by itself.”