Inner Corridor
The space inside the opening was wider than Long Tian had expected. After he stood up straight, there was still more than a hand's width of space between his head and the ceiling, as if it were a passageway designed for passage, rather than a narrow mezzanine. The corridor ran in the same direction as the walls, with smooth walls on both sides. The surface texture was the same as the stone at the top of the wall, without any deposits, as if it had been sealed and kept dry. The air was still, and the temperature and humidity were stable, as if it had been stable for a long time and had reached a state of equilibrium.
The light layer of the Dragon Shadow automatically expanded after Long Tian passed through the opening, evenly illuminating the entire cross-section of the corridor. The corridor extended forward for a distance before slightly turning to the left, with a small bend, but it continued for a while. Long Tian walked forward along the corridor, his footsteps making a uniform sound on the dry ground. The echoes in the enclosed space were absorbed by the stone walls, producing no obvious echoes.
After walking for a while, a narrow vertical groove appeared on the left wall, its width matching the spacing of the teeth on the Dragon Bone Marker Disc. He stopped and ran his palm along the surface of the groove. The aura of the Origin Return Pearl traveled along the inside of the groove, confirming that it was not connected to any additional structure. He continued forward and saw several more similar vertical grooves along the next section of the path, evenly spaced on both sides of the corridor, as if they were used for guidance or positioning.
Yu Jin followed behind into the corridor. His footsteps were lighter than Long Tian's, the sound of them hitting the ground mostly absorbed by the stone walls, and he maintained a pace in sync with Long Tian as he moved forward. He walked to Long Tian's side, glanced at the vertical grooves in the wall, and continued forward without stopping.
After the detour, the corridor extended for about ten zhang (approximately 33 meters), and a more open space appeared ahead, resembling a transverse chamber located within the walls. The chamber was several times wider and slightly taller than the corridor, and its walls were of the same material as the corridor, without any covering layer or sediment. In the center of the chamber's floor was a disc, its edge flush with the ground, its surface smooth and free of sediment, as if it had been continuously kept clean. The disc was the same size as the discs on the underwater paving surface, its surface without patterns or reflections, presenting a matte texture.
Long Tian walked to the edge of the disc, squatted down, and placed his palm on it. After the aura of the Origin Return Pearl was introduced into the disc, a halo identical to the previous discs began to appear on the surface, spreading gradually from the edge to the center. The brightness of the halo was brighter than any of the previous discs. After covering the entire disc, it did not spread further, nor did it trigger any interaction with adjacent structures. It remained in that state after completing its coverage, like a door that had confirmed the identity of the visitor and was waiting for the next instruction, maintaining its own rhythm in the continuous light.
Long Tian withdrew his hand, stood up, and walked around the chamber. There were no engravings or symbols on the walls of the chamber, only a shallow vertical groove in the center of the north wall, its width matching the diameter of the disc, like an inlay. He walked back to the edge of the disc, squatted down, and placed his palm on the disc again. This time, he maintained a continuous output, the aura of the Origin Return Pearl flowing continuously along the surface of the disc, gradually forming a conduction path extending from the center of the disc towards the shallow vertical groove on the north wall. After the end of that conduction path reached the bottom of the groove, the inner wall of the groove began to light up segment by segment, spreading evenly along the inner surface, covering the entire width and depth of the groove before stopping.
Long Tian stood up and walked to the shallow trough. The light layer on the inner wall of the trough maintained a constant brightness, remaining stable throughout. He reached his hand into the trough and probed along the inner wall—the trough was about half an arm's length deep, with a flat bottom and no extra patterns. He withdrew his hand and focused the light layer of the Dragon Shadow into the trough, letting it shine inwards along the trough. When it reached the bottom of the trough, the light refraction revealed a material reflection on the bottom surface that was different from the surrounding stone, as if a layer of dark metallic sheet was embedded there.
He crouched down and reached his fingers to the bottom of the shallow groove, touching the thin sheet. It felt smooth and slightly warm, as if it had been kept at a constant temperature by a continuous flow of energy. He ran his fingertip along the edge of the sheet, finding a tiny seam between it and the stone surface at the bottom. He pressed down slightly along the seam; the sheet didn't move under his pressure, but was gently pressed down a little before springing back to its original position, as if supported by a spring.
Long Tian withdrew his hand, stood up, and took a half-step back. The thin sheet maintained its elasticity during his pressing and rebounding. He walked back to the edge of the disc, squatted down, and channeled the energy from the Origin Return Pearl back into the disc, allowing the energy to travel along the previously established conduction path back to the bottom of the shallow groove. The energy was blocked by the metallic sheet when it reached the surface of the thin sheet, failing to penetrate to a deeper level. After continuously outputting energy for a period of time, Long Tian withdrew his hand. As the energy retreated along the path, the light layer on the inner wall of the shallow groove gradually returned to normal. The entire chamber also returned to its initial state. The halo of light on the disc narrowed and then went out completely. Everything returned to a state of stillness after the lights were turned off.