" The Sea Squirt is one of our most ancient relatives. Its primitive nervous system makes makes it more closely related to humans than the sponges and corals it resembles. As a juvenile, the Sea Squirts tiny brain helps it move towards nutrients and away from harm. Once the Sea Squirt grows to adulthood, it attaches itself permanently to a rock or a boat's hull or pilings. It no longer needs to monitor the world as it did as a juvenile because the passing current provides enough nutrients for it to survive. The adult Sea Squirt becomes the couch potato of the sea. In a surprisingly macabre twist, the Sea Squirt digests its own brain. Without a need to explore or find sustenance, the creature devours its own cerebral ganglia. "

I have actually known a few people like this in my life. They even smoked pot out of pipes that kind of looked like Sea Squirts......