The bursatellin-oxazinin family is a series of tyrosine-derived, nitrile-containing marine natural products from gastropod and bivalve molluscs. Although the first analogs were identified and associated with toxicity 40 years ago, their biosynthetic origins were unknown. During an investigation of published mollusc genomes and transcriptomes, we serendipitously identified a putative bursatellin biosynthetic gene cluster (referred hereafter as the