a safety restraint in an automobile; the bag inflates on collision and prevents the driver or passenger from being thrown forward

a safety restraint in an automobile; the bag inflates on collision and prevents the driver or passenger from being thrown forward

an air-filled sac near the spinal column in many fishes that helps maintain buoyancy

an air-filled sac near the spinal column in many fishes that helps maintain buoyancy

a bubble of air

a bubble of air

a bubble of air

a bubble of air

a bubble of air

a bubble of air