Birds.
Cranial bones contain air spaces. These air spaces are known as skeletal pneumaticity. Bird bones are all filled with air spaces.
a ttrex
Bracchiosaurus A+
a ttrex
Brachiosaurus
It's called 'Bone Marrow' - Bone marrow is the flexible tissue found in the hollow interior of bones. In adults, the marrow in the larger bones produces new blood cells.
Aquatic plants.
The medical term is "paranasal sinuses." These are air-filled cavities located within the bones surrounding the nasal cavity. They are important for natural drainage and humidifying the air we breathe.
air
they have no bones
sinuses.
Birds