In addition to Greg Anderson and Stephen O'Malley, the album features collaborators Tos Nieuwenhuizen, Tim Midyett and Hildur Guðnadóttir.

[6] In the review for AllMusic, Thom Jurek wrote that "The forward evolution of Life Metal has been balanced and extended into a mercurial spirit through formless, receptive interaction on Pyroclasts.

"[8] Jason Anderson of Uncut praised the album, writing that "The results may comprise the most finely distilled example of Stephen O'Malley and Greg Anderson's deconstruction of heavy metal riffage, with each of these tracks demonstrating the infinite varieties of fuzz and rumble that exist within a single mighty note.

"[15] Classic Rock gave the album a 3/10 score, writing, "Four 11-minute 'improvised modal drones' recorded by Steve Albini during the Life Metal sessions for which we're supposed to be grateful.

"[9] All tracks are written by Stephen O'Malley and Greg Anderson[16]Pyroclasts personnel adapted from LP liner notes.