The higher-leveled underground creatures at the edge of the battlefield fixed their eyes on the level-six one that appeared to be upgrading while their vibes started to show some minor changes.
Before, their vibes had been still and stable, but they started to restrain and hide them at that moment. Normally, beasts and humans hid their vibes on purpose and made themselves invisible either to prepare to hunt or do something else.
They didn't make any immediate moves but seemed to be waiting for something.
"The higher-leveled ones have started to hide their vibes. They're going to take action." The group of people had noticed the changes in those creatures.
"They seem to be waiting for an opportunity."
"What are they waiting for? Are they waiting to see the result of the level-six one's upgrade?"
"Could be that, or maybe something else."
Everyone started making guesses about what was happening at that moment.
The humans were paying attention to the whole battlefield while the higher-leveled creatures were staring at the upgrading one, seemingly waiting for an opportunity. Qian Xiaoai and the others all had a feeling that nothing would happen soon, but something would definitely happen at some point.
As expected, they spent four days waiting.
The level-six underground creature that started to upgrade the first hadn't succeeded yet, but some others had started upgrading as well. Their levels varied from three to six. Meanwhile, the higher-leveled ones finally started taking action instead of sitting there and watching quietly.
A level-five one suddenly attacked a level-four one which was upgrading. Within a blink, a level-seven one watching from the edge of the battlefield pounced on the level-five one that was launching a sneak attack.
The level-five one had caught the attention of the higher-leveled underground creatures once it made a move. The level-seven one was much stronger and faster than it. Before it touched the level-four one, it was pressed under the level-seven one's paw and beaten to death before it could react.
The level-seven creature that bit the level-five one to death didn't eat it but threw it to the side and then turned to leave. Before long, the level-five underground beast was eaten by the ones who didn't have opponents at the moment.
The higher-leveled ones appeared to have been maintaining the order of the battle. Of course, that shouldn't be their sole mission. They might be there to serve some other purposes as well.
As the humans were trying to figure out the meaning of those higher-leveled ones' behavior, one creature was finally about to upgrade successfully.
The land had been devastated, utterly damaged. The strong scent of blood rose into the sky, and beast roars were heard wave after wave.
Soon, it became a level-six one. But, instead of joining the battle again, it turned and quickly left the battlefield. The higher-leveled ones didn't try to stop it from leaving either.
Another level-five one failed to enter the new level. Its vibe grew disordered and out of control, and then its energy started to shrink and spread repeatedly, meaning that its upgrade had ended up as a failure. Next, its energy might explode, and then it would die. The energy explosion wouldn't blow up its entire body but twist it.
As the level-five one failed to upgrade, the ones near it that had been waiting for a chance since long ago immediately rushed at it. Another chaotic battle was inevitable.
That was allowed though, as the higher-leveled creatures didn't stop them.
However, when a level-six one failed its upgrading, the other underground creatures didn't dare to rush up and attack it. They wouldn't get anything anyway, because a level-seven one did that before they could.
The level-seven ones seemed to have been waiting for that moment. Unlike them, the level-eight ones made no movements. There weren't many of them though. Only about ten percent of the higher-leveled creatures on the scene were at level-eight.
The level-six ones that had successfully entered level-seven didn't leave as the new level-six had. Instead, they moved to the edge of the battlefield to watch.
"So, the highest level these creatures can reach is seven, right? Aren't those level-seven ones going to upgrade themselves in the same way?" After spending days observing, Luo Yuanjun asked a question.
"Maybe level-seven is a special level. Maybe, they'll have a new way of upgrading at that level. But, I guess they'll still have to kill each other to do that. After all, eating a level-seven mutated animal from the earth's surface won't help them to upgrade," said Li Yueshan.
"Can this be counted as some kind of balance? I thought these creatures don't have any natural enemies. I thought they'd run rampage in the whole world and reproduce endlessly. In that case, the earth would become a dead planet in less than a decade," Qian Xiaoai sighed.
His base and Sea City Base had been studying some kind of herb that was highly harmful to underground creatures recently, but due to the huge population of those creatures, it would still require tens of years to eliminate them, even with that highly effective herb. No one could tell how many plants and animals and zombies would be able to survive in tens of years.
The existence of those underground creatures had been threatening the future of earth much more seriously than the existence of zombies, which fed on humans and their own kind only.
At least the zombies didn't feed on plants.
If all the plants on the Earth were gone, the food chain on the planet would break, and Earth would die in the long run.