However, Ning Shi's former identity, and the fact that she was able to detect the fragments of the pollution source, meant that she might know something.

"I haven't seen it, but one person once told me about the shattering of the source of the pollution." Ning Shi's words were expected by Su Yu.

She did know something.

"I don't know much about it, she only said one thing to me at the time, if one day I also encounter a broken pollution source, then I must destroy all the pollution source fragments as soon as possible, and then destroy them together."

After saying this, Ning Shi paused, and then explained: "I didn't mean not to say this, but I didn't think about it for a while. ”

Ning Shi is not an excuse, she is just busy building barriers, then giving everyone a state, and then investigating the source of pollution...... This was a long time ago, so long ago that she wasn't even a magician's apprentice.

If it weren't for Su Yu who just asked, she would have really forgotten a little.

Su Yu didn't care, and she didn't think she was lying, if she really didn't want to say it, there was no need to answer it now.

"Since you need to wipe out one piece, can you now locate several other sources of contamination?" When Su Yu was asking, she was also thinking about the reason.

After thinking about it for a while, she seemed to understand something.

These fragments of pollution sources are one, and they are only temporarily separated, which does not mean that they cannot be integrated.

If they can't destroy the pieces at the same time, then as the introduction suggests, the pieces will run away after being destroyed.

They definitely didn't run aimlessly, but they fled to other fragments, and then fused with them, so that the fused fragments would definitely be stronger!

After thinking through all this, Su Yu also heard the answer given by Ning Shi.

"I can still find four fragments, but I'm not sure if they're all of them." Just like the previous stone fragments, the largest number Su Yu saw was 'Fragment Four', but this only meant that there were at least four fragments, not that there were only four fragments.

"Anyway, let's go check it out, can you remember where you are?" Su Yu had seen the map before, and her map was originally bright, but after the pollution appeared, her map was also locked and could be opened, but it was pitch black.

And now, although they are still in the space of the underground staircase, they are also a little indistinguishable from the southeast and northwest because of the dark environment around them.

"Yes, I'll just make a mark." Ning Shi made a mark here with the light element, and then led everyone to the location of the next few pollution source fragments.

After running in a circle, more than half an hour has passed, and all the four fragments that Ning Shi can sense have been found, plus the original one, there are a total of five fragments.

Five fragments, but the names are not one to five, the one with the largest serial number is 'six', and they have only found 'one, two, three, five, six', and one less 'pollution source fragment four'.

Su Yu and Ning Shi said that there was a fragment missing, although Ning Shi didn't know how Su Yu could see that a part was missing, she still looked for it seriously, and then shook her head with a frown.

"No, I didn't find any new fragments, and within my sensing range, I could only find these five parts." Ning Shi actually wondered for a moment whether Su Yu had misjudged, but seeing that Su Yu was so sure that there were six parts of the pollution source, she also began to wonder if she had missed something.

"It looks like someone deliberately didn't want us to find it." Su Yu couldn't help but sigh when she couldn't find Ning Shi after trying so hard.

Ning Shi also seemed to understand something, and did not continue to waste his magic.

"In that case...... Let's just get to the bottom of the five pieces. "The sixth fragment definitely exists, but it was deliberately 'hidden', so it's normal that Ning Shi can't find it.

But their time is running out, and they don't have time to find that last fragment for them, and the top priority is to solve the five in front of them first.

As for what happens if all the pollution debris is not addressed at the same time...... Su Yu couldn't think about this anymore, anyway, either clean it up now, or they would just use the Huicheng Stone to leave, in contrast, Su Yu would definitely choose the former, after all, there were still many things that the mermaid clan had not solved here.

Let alone...... Things may not be as bad as they seem.

"Since it is to be eliminated at the same time, what good way does Lord Su have?" Ning Shi asked softly.

While the 'simultaneous' here isn't strict enough to be destroyed in the same second, the interval between the five fragments must not be too long.

If the interval is too long, there will be a situation of fusion, and there is no point in what they do.

"The first method, I have explosives with long leads." It's hard to say exactly how long, but it's definitely enough anyway.

If explosives are used, the explosives are planted first, and then the fuses are placed in similar positions, and then they are ignited at the same time......

Ning Shi was stunned for a moment: "......" is really ...... Simple and crude.

Su Yu couldn't help but smile when she saw her like this, and then vetoed this method herself: "Although the lead is long enough, I didn't bring enough explosives, so there may be some problems with this method." "Although the amount of HP for each fragment is only 10,000, the sum of five is 50,000.

Su Yu had a total of less than 30,000 explosives on his body, which was definitely not enough.

And in addition to the insufficient amount of explosives, this method also has the risk of being easily interfered with by the outside world...... What if a dark creature comes out and kills it while the lead is burning?

Or maybe some dark creatures have removed the explosives they had planted?

Of course, these are secondary, the most important thing is the environment they are currently in, which is underground, and explosives cannot be used lightly, otherwise once it collapses, the consequences will be unimaginable.

"The second method is to arrange people to each of these five positions, and then work at the same time." This method should be something that most people can imagine, but it is also the most difficult to implement.

One is because they don't have a communication channel and don't know what time to do it at the same time.

Second, because when the personnel are dispersed, the output capacity is also reduced, and the more time it takes them to destroy the source of pollution, the longer it takes, the more likely it is to have accidents.

The third reason is similar to the second, it is also because the personnel are scattered, so once a lot of enemies suddenly appear at that time, then they will definitely not have the power to parry.

To sum up: theory exists, practice is difficult.