Named Charlotte, the animal was hit by a boat years ago, causing him to develop an affliction that traps air bubbles at the back of his shell

Charlotte "is doing excellent," is "very comfortable in the harness and is thriving," Dr. Molly Martony, senior veterinarian at Mystic Aquarium, tells PEOPLE

Positive buoyancy syndrome, also known as Bubble Butt, is a serious condition affecting sea turtles. Sea turtles are unfortunately often struck by boats, causing their shells to be deformed. Air bubbles can form in the deformed shell,