Atom Heart Mother, released in 1970, was Pink Floyd's fifth studio album and the first to reach number one on the British album chart. One side is taken up entirely by the title suite, running more than twenty minutes, which the band developed together with composer Ron Geesin using a choir and brass section. The other side contains more restrained songs such as "If", "Summer '68" and "Fat Old Sun", closing with the experimental "Alan's Psychedelic Breakfast". The record marks a transitional phase in which Pink Floyd experimented with orchestral and avant-garde ideas. The sleeve featuring a cow, with no text or band name, became one of the best-known images in their catalogue.