Monniot, C.; Monniot, F.; Griffiths, C. and Schleyer, M. 2001
Mushroom shaped colonies generally found is groups.
Colony consist of round head (2-3 cm in diameter on which the zooids open) on a short stalk (1-12 cm high).
Bright red to deep burgundy in colour.
The surface may or may not contain some sand particles.
Sand particles may be distributed sparsely in the interior test.
Zooids (4-6 mm long) are arranged in circular groups around a common cloacal opening, systems are not conspicuous.
Branchial opening with lobes and the atrial opening with languet which may vary in length.
The branchial sac contain 12-13 rows of 14-18 stigmata.
One to four ova and up to 20 male follicles are present in a sac-like posterior abdomen constricted off the abdomen.
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