Is a video scouring the samples within Slipknot's 1999 debut one of the first times a clip from Slayer's "South of Heaven" has been identified on the album? Or has the twisted portion of the thrash kings' guitar feedback been hiding in plain sight on the masked metalheads' penultimate Slipknot track "Only One" all this time?

At Eightminutesupsidedown — where albums get broken down by the sampling they employ — Slipknot's first got an entertaining rundown that catalogs a wealth of audio samples hidden among its din. As the case may be, some are easier to spot than others. Watch the video down toward the bottom of this post.

It appears some Slipknot fans already noticed the "South of Heaven" sample. At least by last year. A February 2018 Reddit thread posed the question, "Is it known that 'Only One' samples Slayer?" Pointing out the pertinent sections in each song, its inquirer added, "Just spotted this. Sorry if this well known."

Among the scant replies, some said they were unaware of the sound's provenance as part of a Slayer recording. But at least one commenter claimed its inclusion in "Only One" has been "known for years."

At the top of the Slipknot song, a high-pitched, warbled tone can be heard. As shown at about 5:35 in "The Samples: Slipknot Edition," the sound originates from the closing audio feedback in the Slayer selection.

See if you're familiar with the rest of the Slipknot samples in the video, which range from hip-hip recordings by the likes of Ice Cube, to spooky dialogue samples from horror films such as The Exorcist, and more.

As for the origin of samples on other Slipknot albums, the video's creator said they "spent a while researching this and literally drew a blank finding any samples that were on any other album apart from their Self Titled album."

Slipknot's We Are Not Your Kind is out Aug. 9. See their tour dates here.

Every Slipknot Song Ranked