Sea squirt, yep that's me. Sessile in that I planted myself on the beach, but at least I haven't eaten my own brain... yet.
(By the way, these unique creatures are a hot commodity in the research world. They share about 80% of their genes with humans and other vertebrates. They actually start out with a primitive spinal cord. They are cutting edge in genome studies, cancer studies, and fertility studies. Ummm, that part is not like me, guess you guys knew that already, though.)