Leave it up to math-rock geniuses Polvo to name a CD Shapes. What better way to describe the boundaries of music that these lads are always pushing against? "El Rocio" finds the band actually redefining itself with a blissful meandering melody line that's not interrupted by their characteristic pummeling and punctuations. "Rock Post Rock" is an exploration of stringed references, from Ravi Shankar to Ry Cooder, Jimi Hendrix to the southern guitar rock of Lynyrd Skynyrd. "Enemy Insects" is classic Polvo, with its abrupt attacks serving as quotations around the melody. Shapes closes with "Lantern" a beautifully atmospheric piece that essentially does not repeat itself. In other words, it's so open-ended, it has no shape. Get it? --Steve Gdula