Although Tool is not widely considered a metal band as much as they are alternative rock, they're obscure enough to hold reverence for those fans of extreme genres thanks to the members' odd stage presence and occult, obscure, and social structure examinations; only made clear when one takes the time to study their lyrical content; that extends beyond memorizing all of the lyrics to Ænima.
Undertow deserves a spot on the blog for being softer than what was actively considered metal at the time. After all, the album embodies everything metal was at the time, without the intense musical stimulation (they saved that for their visuals and lyrical impact): in it's 20's, angsty and nihilistic. I think Tool has done an irreplaceable job of creating this visual and musical entity that either 1) Completely creeps people out and gets the band banned from your local Walmart or 2) Intrigues the listener enough to want more. And as a metal head, what else compels us to continue down this "path of destruction" for more, faster, better, raunchier metal than the fact that there is mental intrigue? Tool has cornered the market with mental intrigue. Undertow contains classic songs such as Prison Sex and Sober. It's influenced a countless amount of bands and opened a strange door between the booming grunge scene of the early 90's and metal at the time. A complete embodiment of 90's in a unique and re-released album covered album, Undertow is a hidden gem in a complicated tree of what is metal.