ascidian
noun
as·cid·i·an ə-ˈsi-dē-ən 
: any of a class (Ascidiacea) of solitary or colonial sessile tunicates having an incurrent and excurrent siphon
called also sea squirt
Word History
Etymology
New Latin Ascidia, group comprising tunicates, from Ascidium, genus name, from Greek askidion, diminutive of askos wineskin, bladder
First Known Use
1823, in the meaning defined above