Fist-sized, cuboid, transparent, with several tentacles at each corner. Bell robust, nearly as high as wide (1:1.3), slightly rounded but flat on top; diameter to ca. 140 mm; surface smooth. Velarium with numerous branched canals. Rhopalia 4, on sides of bell, in triangular niches ca. 1/6 up from bell margin. Tentacles 24 to ca. 40, each extending up to ca. 3-4 m, banded when contracted, each born on short finger-shaped process inserted on one of 4 palmate pedalia; pedalia robust and inserted on lower 1/3 of bell, bilateral along mid-line. Manubrium 1/2-1/3 bell height, with 4 triangular lips. Stomach wide, round, prolonged into 4 pouches which extend into radial sinuses along bell edges; from each stomach pouch hang two smooth finger-shaped sacs nearly reaching bell margin. Gonads 4, each a thin sheet either side of a radial canal; when mature each extending to meet next laterally.
Coloration transparent excepting tentacles, outer 1-2 typically pale mauve, remainder colorless to pale whitish-yellow.
Dangerously venomous, lethal to children. Chiropsalmus quadrigatus Haeckel, 1880, may be conspecific.