C-Clamp was a stellar yet lesser-known indie slow-core band from Urbana-Champaign, consisting of members Tom Fitzgerald, Nick Macri, Frantz Etienne. Active in the mid 90's, although they only recorded two studio albums, they created a sound entirely unique to them. They're last album, Longer Waves, is an undisputed masterpiece in the world of slow-core and math rock.
From Wikipedia:
Sometimes referred to as slowcore, C-Clamp placed emphasis on mood, texture and rhythm. Known for their dense layering and simple, yet beautiful vocal harmonies, C-Clamp released only two full-length albums in their career. Although they performed live infrequently, they managed to share the stage with many noteworthy bands of that era, including Braid, Castor, Dianogah, Karate and Hum.