by Roberto — Elab­o­rate mech­a­nisms that pro­tect bac­te­ria against phage are well known, with CRISPR lead­ing the way. Less fa­mil­iar but equally fas­ci­nat­ing is the fact that, some­what un­ex­pect­edly, phages them­selves some­times of­fer bac­te­ria pro­tec­tion in harsh en­vi­ron­ments. Fil­a­men­tous phages do just that.