STRINGS.CODEX.PRINCE.BODY.CONTAINER2
A specialized air bladder in the Puft's chest cavity stores varying concentrations of gas, allowing it to control its buoyancy and float effortlessly through the air.
Combined with extremely lightweight and elastic skin, the Puft is capable of maintaining flotation indefinitely with negligible energy expenditure. Its orientation and balance, meanwhile, are maintained by counterweighted formations of bone located in its otherwise useless legs.