Bichordites Plaziat et Mahmoudi, 1988

Diagnosis: Unbranched, horizontal and/or inclined, straight, curved to irregularly winding sediment-filled or hollow structures preserved in full relief. Length and diameter variable; diameter may vacillate along course and tapers at distal extremities. Vertical cross-section circular, subcircular, ovoid, losangic or heart-shaped, consistent or variable along length; commonly, though not necessarily, higher than wide. Upper (dorsal) surface typically with a longitudinal median or slightly eccentric groove, rarely a weak crest; lower (ventral) surface may possess a carina (keel), Typically possesses irregularly developed external constrictions or transverse striations; more rarely smooth.