A 15‐kDa lectin, termed SeviL, was isolated from Mytilisepta virgata (purplish bifurcate mussel). SeviL forms a noncovalent dimer that binds strongly to ganglio‐series GM1b oligosaccharide (Neu5Acɑ2‐3Galβ1‐3GalNAcβ1‐4Galβ1‐4Glc) and its precursor, asialo‐GM1 (Galβ1‐3GalNAcβ1‐4Galβ1‐4Glc). SeviL also interacts weakly with the glycan moiety of SSEA‐4 hexaose (Neu5Acα2‐3Galβ1‐3GalNAcβ1‐3Galα1‐4Galβ1‐4Glc). A partial protein sequence of the lectin was determined by mass spectrometry, and the complete sequence was identified from transcriptomic analysis.