The command center was so quiet you could hear a pin drop, as everyone intently watched the live feed from the robot explorers.
After descending a few meters down the wall, the robot squad reached the bottom of the tunnel.
The observant Jiang Yu noticed that only the exterior of the "Black Square" was pitch black; the interior had turned to a dark gray, clearly made from a different material.
At the bottom of the tunnel, everywhere looked pitch-dark until the robots ventured out and found it was a hall-like structure.
In the hall, four pathways led in different directions; it seemed to be some sort of crossroads.
In the corner of the hall lay many small cubes and rectangles; at one of the pathways, there was even a rectangle resembling a threshold.
Jiang Yu and the staff speculated that among these could be the transportation used by the Black Cuboid People internally, but no one knew which ones or how to activate them.
Upon illumination with ultraviolet light, a variety of small and large frames appeared on the hall walls and small cubes and rectangles, some containing several characters.
The language team studied these characters and found a clear difference from the ones on the "Heifang Cloth Manuscript," confirming these were indeed the language of the Black Cuboid People.
The characters on the "Heifang Cloth Manuscript" appeared to be the outcome of evolution.
The members of the language team stated that the text inside the "Black Square" was extremely hard to decipher and would only be possible after fully understanding the Black Cuboid civilization.
The robot squad's exploration continued as they chose a direction for further probing.
The data lines trailing them were custom-made, since wireless technology had long since taken over and they would otherwise be non-existent.
These data lines were very thin and durable, stretching up to five kilometers; enough for a preliminary investigation.
When one of the robots attempted to emit a radio signal, it found that inside the "Black Square," wireless communication was still impossible.
This was a major inconvenience, perhaps future explorations would have to continue tethered to these data lines.
However, the staff suggested trying neutrino communication or gravitational wave communication, but the equipment was too bulky to fit on a robot and would have to be tested in future explorations.
The interior passages of the Black Square were perfectly flat, around five to six meters high and a dozen meters wide.
The robot squad leader kept the ultraviolet light on, revealing many thick lines forming squares and rectangles on the passage walls.
These rectangles coalesced into intricate and simple designs.
Both sides of the passage had rectangular frames, like doorways, seemingly in two rows of rooms.
After about a kilometer, the path hit a dead end where two new passages appeared.
The robot exploration team chose a direction and advanced a distance only to reach another dead end.
After several directional changes, Jiang Yu and the others saw a hall with several lines dangling from above.
Before they could marvel at this, someone noticed that the robot squad had somehow returned to the entrance.
Reconstructing the robot's path, the team discovered they had traversed an oddly angular polygon.
This path seemed inefficient because it would waste a lot of space, but after careful calculation, the space utilization was surprisingly high.
Before they could discuss this paradox in detail, they decided to have the robots open a room and explore its contents before ending their first exploration.
The robot team chose a room closest to the entrance to open. The floor of this room had gray-black slots, while the ceiling had corresponding gray-black bell-shaped covers.
The command center staff speculated that these covers must have once sat on the slots, forming a sealed environment together.
Gazing at the dense array of slots, what purpose did the Black Cuboid People have for creating so many sealed environments?
Fortunately, in a corner within sight, there was a cover still sealed on its slot.
Several robots immediately moved closer. The gray-black cover did not obstruct their view, revealing some faint yellow liquid inside the glass cover, perfectly sealed from the stone slot with not a single leak.
There appeared to be something in the pale yellow liquid, though it was unclear.
The people in the command center watched eagerly for a while and were about to have the robots approach further when the object in the cover suddenly floated towards them.
Jiang Yu and the others were taken aback, the object in the pale yellow liquid turned out to be a person!
More precisely, it was a child of seven or eight years old, but its lower limbs were underdeveloped, resembling the legs of an infant.
Upon seeing clearly what was inside the cover, everyone was stunned, especially by the sight of the deformed child with pale skin, eyes closed, as if deep in sleep, which gave the room an indescribably eerie feeling.
Then they turned their attention to the rows of empty slots. What had been contained in these slots before? People? Where did they all go?
Quickly afterward, people like Jiang Yu and Wu Zheng who were privy to the situation immediately considered that this might be the very place where the Black Cuboid People "produced" humans years ago.
After these humans "matured," the Black Cuboid People might have transferred their own consciousness into these humans' brains, and thus entities that looked like humans but with the consciousness of Black Cuboid People appeared on Earth.
Wu Zheng ordered the robot to see if it could open the cover.
The robot struggled mightily, but the cover did not budge, so they had to give up.
The first round of exploration ended here.
On the way back for the robot exploration team, the staff in the command center quickly summarized the initial findings of this exploration:
1. The Black Cuboid People's visual receptors undoubtedly differed from those of Earthlings, with their visible spectrum likely being centered around ultraviolet light.
2. The Black Cuboid People's geometric algorithms differed from humanity's, yet were highly efficient. That's why the pathways seemed to waste space at first glance but, upon calculation, were found to utilize space very effectively.
3. There probably were no intelligent creatures left in the "Black Square," as the clean corridors remained dust-free. Thus, no evidence of intelligent life activity was discovered, which would have been expected during the hour-long exploration.
4. The Black Square's intelligent systems might be very weak; at least, the exploration team roamed for quite a while inside and encountered no resistance.
As the robot squad returned, they brought out a small cube from the hall, marking the achievement of the exploration mission.
The researchers named it "No. 1 Cube" and immediately began their investigation.
Jiang Yu took up residence in Black Side City, eagerly awaiting the research results on No. 1 Cube, as well as the next round of exploration.