It is distinguished from the porcupinefish by the shorter, less sharply pointed, and immovable spines which cover the somewhat spherical body. It can inflate its body by taking either air or water into a ventral extension of the stomach. Its color is olivaceous or brownish above and pale yellow below. The back and sides are irregularly striped with brownish, dusky, or black lines which are parallel to each other and which run obliquely downward. There are several large black spots on the sides, one just below the dorsal fin, and another behind the pectoral fin. Its maximum size is about 10 inches.