bur fish

from The Century Dictionary.

• noun A fish of the family Diodontidæ; a porcupine-fish.

from the GNU version of the Collaborative International Dictionary of English.

• (Zoöl.) A spinose, plectognath fish of the Allantic coast of the United States (esp. Chilo mycterus geometricus) having the power of distending its body with water or air, so as to resemble a chestnut bur; -- called also ball fish, balloon fish, and swellfish.