A tall solitary sea squirt usually found in clumps and attached by its base. The body is oval with a fluted oral siphon at the top and an upward-directed atrial siphon 1/3 of the way down the side of the body. The test is grey and semi-transparent, usually covered with lightly adhering detritus, filamentous algae, etc. There is a series of lighter marks around the edge of each siphon, and the large oral tentacles can easily be seen inside the oral siphon in expanded animals. Typical size 50-100mm. Ciona intestinalis always has yellow marks around the siphons, and is different in shape and consistency. Ascidia spp. have firmer tests. Ascidiella scabra is usually smaller and more squat, with both siphons more or less on a level.