Shell large (to 220 mm), elliptical, arched, somewhat convex. Spire depressed, barely in ventral view. Line drawn through apex and anterior tip of row of holes leaves approximately 2/5 of shell towards anterior margin. Holes medium sized, round to oval, considerably raised, usually 2-6 open. Dorsal surface somewhat uneven with bumps and prosocline folds particularly towards the row of holes, with low rounded spiral cords. Row of holes ending in pointed tip. Dorsal surface at obtuse angle to area between row of holes and columella. Area at acute angle to rather narrow columella. Color mostly dull orange-red with radial bands in green, cream, and white. Nacre silvery with pale green, blue, and magenta sheen, irregular surface, spiral sculpture shows in nacre. No muscle scar.

The Japanese H. madaka has larger and more elevated holes, the area between the row of holes and the columella is at a more acute angle, that area is proportionally wider, and a line drawn from the apex through the anterior tip of the row of holes splits the shell in areas leaving approximately 1/3 towards the anterior margin. The Japanese H. discus has a more uneven surface lacking spiral sculpture, and is usually dark green and brown in color.

Japan: Honshu