Sphaerothylacus polycarpus (Sluiter, 1884) has an ascidian for its host.
In accordance with this view there would be also some probability in favour of regarding the collar nerve-tube of the Enteropneusta as the equivalent of the cerebral vesicle only of Amphioxus and the Ascidian tadpole, and also of the primary forebrain of vertebrates.
Further, he includes in it his own Enterognathus comatulae, not from an ascidian, but from the intestine of the beautiful starfish Antedon rosaceus.
Styela gelatinosa is a nationally rare solitary ascidian (sea squirt) which has a soft pear-shaped body about 3-4 cm tall.