As one of the most groundbreaking and analytical pieces of progressive metal, Tool's magnum opus, 'Lateralus,' comes in at No. 1 on our list of the Top 50 Metal Songs of the 21st Century.

Based on the Fibonacci sequence, an intriguing mathematical pattern found in nature, Tool gained the inspiration from the sequence in various ways. Vocalist Maynard James Keenan chose to house the sequence within his verses, creating a syllabic pattern that aligns with the numerical code of Fibonacci's work. The song also switches between 9/8, 8/8 and 7/8 time signatures, with the number 987 being the 17th number of the Fibonacci sequence.

In mapping the numerical representation of the Fibonacci sequence, an eternal spiral shape can be formed, which Keenan uses as a metaphor for finding strength within yourself in the lyric, 'Spiral out, keep going.' The concept of using color as a metaphor for attaining wisdom can also be found within 'Lateralus,' as Keenan describes gaining the ability to see red and yellow after living a life in black and white.

Apart from the concept of 'Lateralus,' the nine-minute track (from Tool's 2001 album of the same name) is a masterpiece even to the casual listener. The innovative cocktail that exists between Maynard Keenan, Adam Jones, Justin Chancellor and Danny Carey cannot simply be manufactured, and as one of music's purest bands, Tool have risen to legendary prominence by simply sticking to their convictions and offering unparalleled depth to their fans.