balloonfish 
noun (plural same or balloonfishes)
A tropical porcupine fish which lives in shallow water and can inflate itself when threatened.
- Diodon holocanthus, family Diodontidae.
- Also called balloonfish, spiny puffers belong to the Tetraodontiformes, an order of fishes known for their strange structures and odd behaviors.
- The conch we saw is safe from the balloonfish because its shell is too thick for the balloonfish to break.