Slender solitary club shaped ascidian with firm cream brown tunic decreasing in diameter to the attachment area.
Body hexagonal in cross-section with branchial and atrial siphon open on upper surface close together.
Branchial sac with longitudinal vessels forming meshes with 2-5 stigmata.
Two long gonads are present on each side containing ova flanked by and testis on both sides.
Endocarps are present on the body wall between the gonads.
Millar, R. H. 1962 Further descriptions of South African ascidians56:113-221
Monniot, C.; Monniot, F.; Griffiths, C. and Schleyer, M. 2001 Ascidians of South Africa.108:1-141
Shenkar, N.; Gittenberger, A.; Ruis, M.; Rocha, R. M.; Swalla, B.; et al. 2017 Ascidiacea World Database. Atriolum marinense Kott, 2001. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=250052 on 2019-03-12