And what was more, several bone spurs, like wings, sprouted from the fish's back, and there seemed to be a thin, transparent membrane covering the spaces between them.

Seeing such a bizarre structure, Number 12 finally couldn't help but ask me, "Do we need to fly inside the undersea tunnel?"

I was momentarily speechless and replied, "Well... I really don't know."

The three of us looked at each other, unable to fathom why this fish's body had evolved into such a configuration.

With no other option, I continued to wipe the pattern upwards.

The next part of the pattern was positioned beyond the limit of my height, so I had to use my telekinesis to wipe it clean from a distance.

This way, the pattern slowly materialized, almost as if by magic.

Before describing this mural, I must insert a small digression.

In the theory of evolution, although mammals evolved from amphibians, the distant ancestors of humans were not dinosaurs; dinosaurs most likely eventually evolved into birds.

Mammals, however, evolved from another branch of amphibians. As for how amphibians evolved into the more advanced mammals, this remains a missing piece in biology, but our ancestors and the ancestors of the dinosaurs were definitely not from the same lineage.

In the painting before us, the initial amphibian became smaller, shedding the scaled body and the fierce jaws and teeth characteristic of crocodiles, becoming leaner and more compact.

Furthermore, this creature didn't just have a shorter face; its body grew soft, downy fur, and it trailed a long tail, the tip of which was bushy like a squirrel's, giving it an appearance of exceptional agility.

I already knew how Number 12 would react upon seeing this depiction, as I had the exact same reaction the first time I encountered the ancestor of mammals during my initial study of biology.

Which was to exclaim, "A rat!"

That's right; the ancestor of us humans and all mammals, the very first mammal to exist, was called the Purgatorius, and it looked almost identical to a rat.

Some scientists have predicted that if humanity were to become extinct, the creatures most likely to dominate the world and evolve intelligence would be rats, due to their incredible vitality, adaptability, and reproductive capabilities that surpass even those of humans.

This might be a coincidence—that the ancestor of mammals and the highest form of mammals share such a striking uniformity.

Unexpectedly, Number 2 chimed in, "That's the Purgatorius, your ancestor! Are you trying to shorten your lifespan by calling it a rodent?"

Number 12 blinked, turned to me, and asked, "Is that true? Is this really the ancestor of all mammals?"

I nodded, explaining, "Indeed. But look closely; the Purgatorius still differs significantly from modern rats. For instance, its legs were longer and more curved, and its tail had fluffy hair. There was a reason the first mammal evolved this way. When mammals first appeared, dinosaurs roamed the land, pterosaurs ruled the skies, and there were all sorts of reptiles, even many carnivorous insects with wingspans exceeding five or six meters. As warm-blooded creatures, these first mammals were vulnerable. They could only survive by having smaller bodies and more agile movements to evade predators. To be more nimble in the trees, they developed long, specialized tails. Considering all these factors, this form was the most suitable for survival."

At this, Number 2 added, "Hear that? If the Purgatorius hadn't looked like that, you wouldn't be here today."

Number 12 grinned, saying, "Got it, got it!"

We all laughed heartily and then moved on to examine the pattern to the right.

At this point, we saw that the strange, winged, crab-legged fish was finally undergoing a significant transformation.

This time, it completely broke free from the shell's constraints, and even those crab-like legs had degenerated. The entire body resembled a tailless salamander—smooth, scaleless, completely black, and possessing a pair of large eyes without a discernible white sclera.

The bony spines and thin wings on its back had morphed into three pairs of wings resembling those of a dragonfly, and two rows of eight large suction cups were arranged along its abdomen.

This evolution seemed to reveal a clue to me; after all, I had studied biology extensively. If the previous stages of evolution still carried unnecessary remnants of the preceding species, the creature before me had now become a perfect organism.

I was hesitant to be certain until I observed its environment, at which point my hypothesis was confirmed.

This peculiar, suction-cupped salamander clung to the side of a horn-shaped cavern opening, adhering tightly to the sheer cliff face next to the entrance, suspending itself on the vertical rock, silently enduring the swirling dust storms.

So I began to speak, "The streamlined body, like a salamander's, minimizes drag; the suction cups beneath allow it to cling firmly to the cliff; and the six wings on its back enable stable flight in the wind, preventing them from being broken."

Number 12 nodded repeatedly and said, "If that's the case, this creature's habitat must be extremely harsh, with strong winds every day. So, this place might not be the seabed but a high-altitude cliff. Our previous deductions were wrong. Perhaps we could find fossils of this creature on the cliffs of the Himalayas!"

I was at a loss for words, as I couldn't fathom the connection between the previous cavern and the cliff face.

This creature had clearly survived within the cave for a substantial period, long enough to evolve into this form—a process that must have taken at least a million nian (years/time units).

Life within the cave must have been grueling, so why didn't they leave earlier? Did they spend that million years constantly traversing the cave? Just how long was this tunnel?

The longest cave in the world is only about a hundred kilometers. Even for such a small creature, crawling with crab-like legs, it would take at most a year to traverse. A passage this long could only mean it wasn't on Earth, but rather a conduit connecting Earth to another space!

Thinking of this, I hastily looked at the circle enclosing the creature. The number marked below had indeed changed to "0016-0018," and "0017" had vanished without a trace.

As I saw this, sweat beaded on my forehead, for I seemed to understand the significance of these numbers!

This truly was earth-shattering news.

With this realization, I disregarded whether any new species had appeared on the line connected to my head and immediately wiped further upward.

At this moment, all the lines connected to the upper regions pointed toward a single location, as if the three lines were about to converge.

Observing this trajectory, driven by overwhelming curiosity, I wiped away all the debris covering the entire door.

As dust billowed away, we witnessed a scene that stole our breath.

At the apex of all the connecting lines was a string of Arabic numerals—all lines converged here.

The Arabic numeral was "0016!"

We stared at the number engraved on the door panel above us, speechless for a long moment.

The numeral was etched with extreme subtlety, lacking any distinct font or embellishment, nor was it highlighted or enlarged. These few Arabic numerals blended perfectly and harmoniously with the biological depictions, causing no sense of incongruity whatsoever.

Yet, for some inexplicable reason, seeing these mundane numbers suddenly weighed heavily on my spirit. It felt as if these digits weren't just crowning this stage of evolution but were pressing down directly upon my chest, like a massive boulder making it hard to draw a breath.

Before I could process this emotion, I heard Number 12 suddenly begin to weep softly beside me.

I turned to see Number 12 wiping away tears, her expression one of profound sorrow.

And Number 2 bowed his head, murmuring Amitabha softly.

Suppressing the gloom in my own heart, I asked, "What's wrong with you two? Have you been poisoned by some microbe again?"

Number 12 dabbed her eyes as she spoke, "No, it’s just... just that for some reason, seeing these numbers makes me overwhelmingly sad, I have this urge to cry."

Number 2 also said, "I don't know why either, but my mood feels much heavier."

In reality, I felt the same inexplicable sensation as they did, but the strangeness of this feeling made one suspect some external manipulation might be at play.

After a period of heavy silence, I slapped the stone door. "Stop crying. Don't let the eerie atmosphere of this tomb affect you. We've finished looking at the images on this door. Although the conclusion is inexplicable, there are no more clues here, so we must open this door now and see if there are any remaining clues inside."

Though still looking somber, both of them nodded at me.

I turned my head to look at the door, thinking, It’s easy to say we need to go through, but we still haven't found the mechanism. What should we do?

Just as I was thinking this, the Yehuo (Netherflame) in Number 2's hand suddenly began to crackle and pop.

In the flickering shadows cast by the firelight, a dark silhouette flashed past us, stirring a gust of chilling wind.

I shivered, my heart tightening. Before I could react, the stone door before us began to rumble as it rose upward.

I stared at the slowly ascending door in bewilderment, exchanging glances with the other two.

Though the principle remained a mystery, the door was opening, so there was no reason to retreat.

I took the lead, ducking low to slip underneath the stone door, preparing to scout ahead.

But the moment my head passed through, the light from the Yehuo behind me illuminated a terrifying, stark white giant face, its empty eyes staring at me malevolently, its mouth full of fangs glittering eerily in the dim light.