Three hours after the all-clear, Chen Hao stuffed the last sampling seal strip into the recycling bin and turned to walk towards the equipment room. He didn't speak, but his steps were a beat faster than usual. Susan glanced up at him from the monitoring console, then looked down at the screen—the yellow dot in the F5 tank was still there; the concentration hadn't changed, and it hadn't spread.

"Are you going out to sea?" she asked.

“We’re just sitting here anyway.” Chen Hao opened the cabinet door and began inspecting the seams of his wetsuit. “We can’t just watch those bacteria colonies grow.”

Carl, carrying his toolbox, stopped when he heard this. "Aren't you afraid of bringing back something else?"

"I'm scared." Chen Hao buckled his helmet. "But the base can't survive on just growing vegetables. We still have to investigate."

Nana stood at the end of the passage, her mechanical eyes flickering slightly. "The sonar system has been restarted, and the backup frequency band is available. We recommend prioritizing scanning the depression to the east, where hydrothermal activity has decreased and signal interference is reduced."

“Then let’s go to the east.” Chen Hao patted her shoulder. “Don’t just talk the talk, walk out the map.”

When the four were fully equipped, the daylight simulator had just been switched to dawn mode. They didn't have to wait long before the base's airlock slowly opened, seawater rushed in, and after the pressure was balanced, the team rappelled down into the deep sea along the guide rope.

No one chatted during the descent. The last mission brought back trouble instead of hope, and no one could guarantee that this time wouldn't be worse. Chen Hao gripped the probe tightly, his eyes fixed on the gray water ahead. The outline of the rock formations slowly emerged under the searchlight, like a pile of crooked stone tablets.

Nana's voice came through the communication channel: "Anomaly detected in gravity gradient, azimuth 217, distance 1200 meters. Preliminary assessment: enrichment of high-density material."

How tall?

"Equivalent to 3.8 times the volume of granite of the same size."

Carl whistled: "Either it's iron ore, or we've stepped on an alien spaceship."

"Don't get ahead of yourself," Susan cautioned. "That 'super vegetable' almost ruined the entire farm last time. Now we have to be a step behind everything else."

The team adjusted its direction and advanced towards the target area. As the depth increased, the temperature dropped, and the water currents became turbulent. The red dot on the navigator flickered several times, deviating from the original route.

“There is magnetic interference,” Nana said. “I suggest you take a detour and avoid the central strong magnetic field area.”

How do we get around it?

“Go up the left slope for 30 meters, then cut in laterally.”

Chen Hao nodded, "Do as she says."

They moved slowly, hugging the rock face. The detector continuously emitted short pulse signals, the echoes forming blurry outlines on the screen. After a few minutes, the terrain began to change; a wide crack appeared in the ground, revealing complete darkness below.

"Is this the abnormal zone you were talking about?" Chen Hao stopped.

“Right below.” Nana brought up the 3D projection. “There is a continuous metallic reflective surface on the west side of the fissure, about 200 meters long and estimated to be more than 15 meters thick.”

“It doesn’t sound like it was formed naturally.” Carl leaned closer to examine the drawing. “So perfectly regular?”

“Large mineral veins also exist in nature,” Susan said, “but this level of purity and distribution… is truly rare.”

Chen Hao stroked his chin. "Let's go down and take a look."

They descended the slope, approaching the edge of the fissure. The rocks here were dark in color, covered with a thin layer of mud. Chen Hao gently scraped away a section with his probe, revealing the silvery-gray rock layer beneath.

“The color is wrong,” he said.

Nana moved closer to the scanner. "The surface layer contains less than 5% iron, and the main component is an unknown alloy. Preliminary analysis shows that its crystal structure is highly ordered, and it is an atypical geological sedimentary product."

“I don’t understand,” Carl said. “Can we dig?”

“We can try taking a sample.” Susan opened the portable drill. “But the surface is too hard; a regular drill bit won’t last more than a few seconds.”

“Use the needle we got from the ruins.” Chen Hao turned around. “It’s the one Karl kept using as a screwdriver.”

“That’s a high-density probe!” Karl protested. “I’m counting on it to fix the reactor!”

"The reactor isn't broken." Chen Hao held out his hand. "Give it to me."

Carl hesitated for a few seconds before finally pulling a thin, long metal rod from his toolbox. It was jet black, with a sharp, thorn-like tip. He handed it over with a pained expression.

"It can only be used for five minutes."

Chen Hao took it and inserted it into the drilling rig interface. The machine started with a low hum, and the probe slowly sank into the rock strata. There was no reaction for the first two seconds, but in the third second it suddenly sank, disappearing one-third of the way in.

“I wore it!” he said.

When the drilling rig retracted, it brought out two rock cores, one intact and the other broken. Susan immediately took them and placed them into the testing instrument. The screen lit up, and the data stream scrolled rapidly, but the values ​​kept fluctuating and could not be locked.

“The readings are unstable,” she said. “High-pressure environments affect sensor accuracy.”

“Offline analysis.” Nana took the sample box. “Use the local database to reverse-engineer the elements.”

She remained motionless, her body trembling slightly, and fine mist of water vapor emanating from the vents. Twelve minutes later, her voice rang out again.

"A new transition metal alloy has been discovered, tentatively designated as X-9. It possesses ultra-high conductivity, compressive strength more than thirty times that of ordinary steel, no radioactive residue, and excellent corrosion resistance."

The scene was quiet for a few seconds.

Then Chen Hao laughed: "We're rich!"

“It’s not just about money.” Susan looked at the data. “If this material can be processed, it can be used to make a new generation of shells, cables, and even power frames. Our diving equipment could be upgraded by a generation.”

"It can also be used as a pot," Chen Hao said. "I won't have to worry about instant noodles exploding anymore."

Carl was already squatting on the ground, examining the rock core. "Look at this cross-section, isn't the reflection a bit strange?"

The group drew closer. The fracture revealed a grid-like pattern, resembling a regularly arranged microstructure within.

“It’s not a natural crystallization,” Nana said. “It’s more like the result of some kind of directed growth.”

"You mean...this mine was created by humans?"

"The cause cannot be determined at present. However, judging from the molecular arrangement, there may be traces of external energy intervention."

Chen Hao tapped the rock wall. "So this isn't stone, it's a finished product?"

"Possibly."

He grinned and said, "Then we didn't find resources, we found a factory warehouse."

The team continued their exploration along the edge of the fracture. Nana deployed three miniature drones, which flew close to the ground, continuously transmitting images. Twenty minutes later, the mapping was completed, and a complete outline of the ore vein appeared on the terminal.

It extends in a band-like shape, with an average width of eight meters and a maximum thickness of twenty-one meters. Part of it is exposed on the seabed surface, while the rest is buried under sedimentary layers. Its overall orientation is parallel to the nearby fault lines, with localized cracks running through it.

"The area is quite large." Chen Hao zoomed in on the northwest corner. "This area looks the most stable."

“Yes.” Susan pointed to a protruding rock base. “There is a supporting structure on the west side, which is not easy to collapse and is suitable for setting up a temporary work site.”

“Then let’s go with this place.” He brought up the marking system. “Set up a beacon and name it Alpha-mining point.”

Carl adjusted the frequency and locked the main control terminal in place. A red dot flashed and fixed itself in the center of the map.

"The signal is normal; remote access is possible," he said. "Should we add a password?"

“Add it,” Chen Hao said. “Set it to my birthday.”

When were you born?

"I don't know, just set any six-digit number."

Susan shook her head. "We need to make a record sheet, including the sampling time, location coordinates, and environmental parameters, otherwise we won't be able to tell where each place is next time we come."

"You write it," Chen Hao said, handing over the tablet. "I'll think of a name."

“How about calling it ‘Iron Lump’?” Carl said.

"That's so corny." Chen Hao looked at the mine wall. "This thing glows blue; it's called 'blue gold.'"

"It sounds like cold medicine."

"Then let's call it 'Hard Goods'."

"It sounds more like black market trading terminology."

Nana suddenly raised her hand. "A slight vibration was detected, lasting for 3.2 seconds, originating directly below."

Everyone stopped what they were doing.

"earthquake?"

“Low probability,” Nana analyzed. “The energy release is concentrated and decays rapidly, more like a local collapse.”

"Is there a problem with the ore body itself?" Susan asked.

“It cannot be ruled out.” Nana pulled up the stress model. “Some areas are under pressure close to the critical value. If they are subjected to external impact again, a chain reaction of ruptures may occur.”

Chen Hao stared into the depths of the crack. "So, this precious land beneath our feet could collapse at any moment?"

“The risks are manageable in the short term,” Nana said, “but I do not recommend large-scale disruptions.”

"Understood." Chen Hao nodded. "That's all for today. Take the samples back, we'll talk about the rest next time."

He took one last look at the mineral wall, which gleamed with a faint blue light, and reached out to touch its surface. It was cool and smooth, unlike stone; it felt more like some kind of cooled metal casting.

"Who told you to leave this behind?" he said in a low voice.

No one answered.

He withdrew his hand and prepared to turn around.

Just then, the probe suddenly emitted a short beep.

Chen Hao looked down at the screen and noticed the signal strength had jumped.

It did not originate from the ore body.

It's underground.