Haliotis exigua: Shell small to medium sized (to 40 mm), oval, lightweight, somewhat arched, hardly convex. Spire depressed, visible in ventral view. Holes medium sized, round, a little elevated, usually 4-5 open. Dorsal surface with approximately 25 low, square, spiral cords of variable thickness; overall somewhat uneven. Color muddy green and brown with irregular white markings. Columella of medium width; truncated at anterior margin. Nacre steel blue. No muscle scar.

Shell medium sized (to 114 mm: Hutsell et al., 1997 [as H. aquatilis]), oval oblong, light to medium weight, somewhat arched, convex. Spire little elevated, usually visible in ventral view. Holes rather small, oval, slightly raised, usually 6-10 open. Dorsal surface with regularly alternating fine scaly spiral cords of round profile, or irregular sized spiral cords of low square profile, with irregular strong radial growth lines; some specimens smooth. Profile from suture through row of holes to columella describing smooth curve. Acute angle at transition to columella. Color highly variable, maroon, rust, brown, green; with cream and white markings. Coloration highly variable, unicolor, with large blotches, large to fine mottling, large to fine tenting, often with abrupt color changes at radial growth lines. Columella narrow, set off from anterior margin. Nacre silvery white with blue sheen, with more or less distinct spiral grooves. No muscle scar.

Haliotis exigua: Haliotis glabra from the Philippine area is rounder, has an almost smooth shell, is sturdier, and the holes are almost flush with the dorsal surface of the shell. Haliotis diversicolor from southern Japan and the lndo-Malayan Archipelago is much less depressed (more elevated spire, more arched, more convex), is more elongated in outline, and does not have a bend in the shell at the row of holes.

Haliotis exigua from Okinawa is much more depressed, is more circular in outline, and has a distinct angle at the row of holes. Haliotis discus from Japan has an undulating dorsal surface, a thinner shell, more elevated spire, more elevated holes, and has a distinct angle at the row of holes. Haliotis tuberculata from the European region is more arched, has more elevated holes, a broader columella, and often elevated radial folds. Haliotis squamata from Western Australia and the Indo-Malayan Archipelago is more elongated, more arched, and has scaly spiral cords.

Haliotis exigua: Type locality: Sea of Japan. From Dunker's (1877) title (cf. Talmadge, 1963a: 136). - Okinawa.
Range: Mostly southern Japan: Okinawa, with some additional localities

Southern Hokkaido (Japan), China, Taiwan, Bali