A new structural model of bivalve ligament from Solen grandis

► We first studied the ligament structure of Solen grandis. ► We found a unique protein fibrous layer in this ligament. ► Aragonite fibers in the ligament are zigzag in form. ► We proposed a new three-layered structural model of bivalve ligament. ► This model is ubiquitous in Solenidae ligaments, which may inspire in bivalve classifications.