Let's start with the point of consensus: Altar of Plagues is a metal band from Ireland. The group is probably a black metal band, except they incorporate elements of sludge metal, drone, atmospheric metal à la Jesu, grindcore and even traditional Irish music. And I don't mean traditional like the Pogues; track 3 of their stellar new record, Mammal, "When the Sun Drowns in the Ocean" features keening, an ancient vocal lament performed by one or several woman as part of a funeral service. It was abolished by the Roman Catholic Church, so including it here is secretly metal.

Also, it sounds creepy/cool.

At just over eight minutes in length, "Sun" also manages to be perhaps Mammal's most accessible track, by which I mean it's the shortest. Bookended by the keening, the tune is nothing if not haunting. At the four-minute mark, it morphs into a heavy metal thumper. The guitars are certainly dissonant, but there's still an underlying ambience to the whole thing that complements the keening's surreal qualities.

The song that really defines Mammal, however, is "Neptune Is Dead". It's the opener, and it's nearly 19 minutes long. Skip that track, and you lose almost half of the album right there. Mammal's songs take a while to get going, and "Neptune" is no exception. A mechanical hum gently fades into guitar squalls over the course of a minute. Drummer Johnny King starts to poke through with some flourishes, and by the two-minute mark, "Neptune" launches into a thrashing noise that rivals anything Napalm Death ever accomplished. It's loud.

Nineteen minutes is a long time to devote to just one song, but Altar of Plagues isn't a stoner rock band–the tune packs enough movements to keep things interesting. Besides, the track listing is almost superfluous. Outside of "Sun", differentiating between tracks is pointless when there's shredding to be had. This need to constantly move, to jump from one subgenre to the next, keeps Mammal alive. It's a record that encompasses elements from several styles and creates something new. One general criticism against metal is that it gets homogenous somewhere between the solos, screaming and chugging. That could never be said of Mammal. Whether they're rocking a blast beat or showcasing ancient Irish musical styles from a thousand years ago, Altar of Plagues has crafted one of 2011's most unique metal albums.