The British band Squid keeps testing its limits—and the limits of those who would try to define it. Since 2017, the group has released a string of new songs, each a bit weirder than the last, up through last month’s “Pamphlets,” another in a growing constellation of oddities. The band is composed of five musicians, each of whom has multiple roles: the singer and drummer Ollie Judge, the guitarist and vocalist Louis Borlase, the guitarist and vocalist Anton Pearson, the bassist and brass player Laurie Nankivell, and the keyboardist, cellist, and percussionist Arthur Leadbetter. The project originated with Judge, Pearson, and Nankivell playing together in a soul-and-funk covers band. They also shared an appreciation of the German Krautrock band Neu! From these disparate influences, Squid has built something protean and compelling.