Sidereal Iron of the ZU

Often labeled “jazz-core”, Zu stand out for their complex rhythmic structures and the aggressive use of instruments, especially the baritone sax, played in a percussive and distorted way. 
In January 2026 they released the album Ferrum Sidereum, welcomed by critics as one of their most significant and darkest works, the only one I’ve heard from their prolific career, and I consider it a masterpiece that pushes me to listen to the earlier albums too.

Not easy to review the tracks: they required several listens, and below I try to convey what they left me, across about 80 minutes total, with long pieces ranging from roughly 7 to roughly 10 minutes. 

Charagma opens the album with ambient noises—rain, thunderstorm—followed by the attack of a heavy riff of distorted bass and bleak, dark sounds. A tense mood. Dissonances. Powerful drums. Chaotic climate with a strong metal component. Unsettling synth pads. Percussive hits in the opening with the syncopated riff and then drums only. Riff repeating. Horns that launch an alarm-like sound, almost archaic. In the final part a heavier mood and controlled chaos. Bass that scratches and lays the foundation with firm strikes.    

Golgotha starts with distant synth sounds and a loop with a cinematic mood like Darth Vader’s advance. The same figure gets heavier. Then it rises again and turns into dark metal; the keys climb, drawing a powerful bed over the heavy stride of bass and drums. Definitely prog metal. Great drumming. Then it speeds up. Horns almost hypnotic. It drops in tone mid-track onto a rhythmic, almost tribal percussive bed, with unsettling background sounds. It grows progressively in intensity into a grim march.  Again an atmospheric suspended moment made of synth sounds before a heavy restart with aggressive bass, powerful drums, and horns with very long tones and a beautiful solo—tense, emergency-like mood.    

Kether begins with percussive, almost echoing sounds followed by bass and guitar in a long intro in which the rhythmic base becomes more and more defined, from syncopated sounds to a hard-and-pure beat, heavy, followed by bass and synth. Beautiful tense atmosphere. The initial figure returns and the percussive base returns. The waiting mood returns. Then the powerful bass and the syncopation in an escalation that progressively grows harsher up to a suspended moment where the guitar draws the rhythm that underpins the variations of drums and synth. The weave becomes more melodic without losing the driving, relentless edge up to the explosive, epic, intense finale.  Monstrous bass lines.

A.I. Hive Mind has an immediately chaotic start, built on a synchronous syncopation of drums, bass and guitar with horns in dissonance that quickly evolves into an intricate texture. A sense of urgency and emergency constantly growing. The electric piano comes in, alternating more suspended phases with phases where bass and percussion turn dark. Then, in a concert of dissonances, odd meters and distortions, the piece resumes its run. We’re on the border between improvisation and, at times, psychedelia. Sounds that at times become ethereal. The imperious bass defines the mood through its accents, figures and breaks. Great guitar and horn interventions. 

La Donna Vestita Di Sole starts with a long, monumental ambient intro with echoing drums over a synth bed. Bass that sculpts the air with deep sounds. The synth bed grows progressively up to a machine-gun burst of powerful, dissonant drums, guitar and bass.  Then a guitar figure that changes the sonics and becomes an anxious run of sounds that add to the powerful underlying rhythm. A gripping and ruthless track.

Pleroma has an ambient intro: bass and synth sounds and cymbals, bells. Soft tension and a mood of waiting. A prolonged atmosphere that shifts into a slow rhythm dominated by the ever-present bass and an essential, almost electronic drum base. Distorted basses move forward slowly while a percussive substrate grows out of silence and becomes continuous and relentless over a bass loop and increasingly chaotic synth sounds, up to a controlled explosion where the hypnotic, intense horns return, fading out.

Fuoco Saturnio. Lovely the opening guitar arpeggio in an atmosphere that immediately turns into a fast guitar riff followed by a driving rhythm. Many rhythmic variations with splendid bass–drums synergy marking syncopations and breaks of unpredictable shapes, thickening more and more until they determine a dark, raw metal phase with machine-gun bass bursts and, as soundtrack, a slow litany of sharp, distorted horns and synth—mad bagpipes—while bass and drums scratch. 

The Celestial Bull and the White Lady has a celestial beginning like the title, with a relaxed melody over which a raw guitar figure and distant acoustic percussion immediately enter. The intensity grows and percussive elements, plates and cymbals are added; the guitar riff becomes more decisive and, with the bass, turns imperious. A triumph of offbeats and polyrhythms up to a suspended phase—long and slow—with an epic atmosphere that flows into a final run, with a metal mood and the dark flavor that dominates the last minutes, in a constant acceleration. Magnificent.

Hymn of the Pearl. Beautiful the long hypnotic intro with an evocative, atmospheric loop of synth and echoing percussion that thickens more and more, increasing the emphasis but without losing the steady stride, up to a decisive guitar figure that speeds up the tempo and makes the rhythm section stronger.  The initial theme returns, ever more gripping. The bass bed is deep and unsettling up to an insert with a very dark sound, marked by bass and synth hits and a drum part rich in nuances. A piece dominated by an atmosphere of unsettling ожидание and marked power in all its phases. Spectacular, epic in every sense, with an ending that comes too soon despite its over nine minutes.

Perseidi is an atmospheric interlude that links, with splendid gliding synth sounds, the previous track to the next one

Ferrum Sidereum is born on the fade-out of the sounds of the previous track, over which an imperious bass figure of extraordinary intensity enters in a long, tense crescendo. When the deep, powerful drums come in, I’m already captivated by the mood of urgency and gravity. A triumph of emotions, among which there is room for a more acoustic and ethereal section. But it’s only a brief pause. The organ and drums, with the inevitable imperious bass, immediately return to mark powerful breaks that grow more complex as the keys rise in volume and drums and bass draw spectacular progressions. Then the explosion: controlled chaos in what is a splendid gallop of syncopations that split the air into ordered, strident fragments. Faster and more dissonant. Toward the end, up to repeated machine-gun shots interrupted by brief pauses in which the echoes of taut skins and cymbals resound. Masterpiece.

An album that initially threw me off but that, already from the first listen, was thrilling. The many listens are not due to the need to understand it, but rather to confirm the initial sensations that I reported in my description of the tracks, which I hope sufficiently summarize my opinion of this record—one I prefer to leave in the world of emotions rather than in cold, rational technical judgments. 

In a few words, I define it as an essential, magnificent album, TOP of 2026 so far.

My Version

Label: House Of Mythology – HOM 037
Format: CD, Album, Stereo
Country: UK
Released: 9 Jan 2026

Tracklist

1. Charagma (6:43)
2. Golgotha (7:13)
3. Kether (7:15)
4. A.I. Hive Mind (8:23)
5. The Woman Clothed with the Sun (9:23)
6. Pleroma (7:37)
7. Saturnian Fire (6:00)
8. The Celestial Bull and the White Lady (8:04)
9. Hymn of the Pearl (9:16)
10. Perseidi (1:04)
11. Ferrum Sidereum (8:49)

Duration 79:47

LineUp

- Massimo Pupillo: bass, 12-string guitar, synthesizer, keyboards
- Luca Tommaso Mai: baritone saxophone, keyboards, synthesizer, organ
- Paolo Mongardi: drums, acoustic and synthetic percussion

Listening links via the main digital platforms: 

• Bandcamp: The best option to support the band directly. You can stream the tracks and buy the album in digital or physical format on their official Bandcamp page.
• Spotify: The full album is available for free streaming (with ads) or premium here on Spotify.
• YouTube: You can find the whole record uploaded on their label’s channel, House of Mythology, in this Full Album Player.
• Amazon Music: Available for streaming and purchase in MP3 or CD format on Amazon Music.
• Apple Music & Deezer: The album is also available on Apple Music and Deezer. 

Note: All links to the musicians' works are in the TAGS under the article title or on the page "Artists"