Experiment Concluded

The reason that "Filth" was regarded as the strangest mysterious phenomenon was that after the misfortunate research staff saw the picture, a black spot appeared around his ankle.

The black spot was only around the size of a fingernail. It may have gone unnoticed if not for Chen Chen performing a full body check on the research staff.

It was only after Chen Chen ordered the researcher to strip naked when the member complied unwillingly and discovered the inconspicuous black mark around his ankle.

The reason it was difficult to notice was due to the contrast of skin color. After all, 90% of the research staff Chen Chen hired in Namibia were black people whose skin tones were considered darkest among their peers.