This species is a compound, colonial ascidian, with small, individual zooids embedded in a common matrix or tunic. The colony can grow extensively, covering large areas of substrate. Colony shape varies from encrusting sheets to long, irregular lobes, with layers often growing more than 4 mm in thickness. Individual zooids are very small, measuring approximately 1 mm. The tunic also contains microscopic calcareous spicules; however, these spicules are not abundant and are mostly confined to the surface layer of the tunic. Each spicule measures up to 58 μm (average 30 μm) in diameter and shaped like a multi-rayed star (8-11 rays). The tunic surface is characterized by narrow, spicule-free dark lines that meander between groups of zooids. Overall color varies from creamy white, pale yellow, or beige to pinkish or pale orange. See Lambert, 2009 for more detailed description.