Assertion: booby's skull | /r/HasProperty | filled with air
Facets:
value: to serve as a cushion
type: PURPOSE
Source sentences:
text: Special adaptations allow blue-footed boobies to barely be phased by the impact they experience during hunts: they have protective sacs around their skulls, which are filled with air to serve as a cushion for their birdy-brains when engaging in their ritualistic searches for food.