We conducted a review of flagellin proteins in the UniprotKB database and uncovered the wide diversity that exists in the length of flagellins. Bermanella marisrubri DSM23232 was predicted to produce a particularly large flagellin with over 1,000 amino acids. We showed by negative-staining transmission electron microscopy that it also produces an unusually thick flagellar filament. To confirm the identity of our cultures and that the predicted gene was present, we sequenced the genome.