Diagnosis: Shell turbinate; 5–8 granulose ribs at and above periphery, single thread between each rib,granules not aligned in axial series; white with faint fine brown marbled pattern.
Mature shell height 4.4–12.8 mm. Shape high turbinate (H/B = 1.19–1.51, SH = 1.36– 1.69); spire whorls rounded, suture distinct; spire profile straight; periphery of last whorl weakly angled at periphery and sometimes also at shoulder. Columella concave, hollowed and slightly pinched at base; eroded parietal area; often an imperforate pseudumbilical area adjacent to columella; often a slightly produced anterior lip to aperture. Sculpture of last whorl: 5–8 strongly or weakly granulose ribs at and above periphery; granular sculpture not usually aligned in axial series; ribs usually subequal, but peripheral rib and shoulder rib may be slightly more prominent; single thread between each rib (rarely two or none); spiral microstriae cover entire surface; base with 4–8 ribs; surface usually eroded. Protoconch 0.28–0.30 mm diameter, 2.9 whorls. Colour: dirty white, fawn or pale blue-grey, spire whorls blue-grey to purple-brown; pattern usually faint, sometimes absent, brown marks between granules on ribs, brown marbling over whole surface in darkest shells, but with cream spiral line on base and another adjacent to columella; aperture brown with pale band at base; columella brown.

Of the few sympatric species, confusion is only possible with E. vidua; the shell of E. radiata differs from that of E. vidua in its slightly taller spire, profile often slightly angled at periphery and shoulder (rounded in E. vidua), usually larger and coarsely granulose ribs with single thread between (finer and more numerous ribs and granules in E. vidua), dirty white colour sometimes with indistinct brown pattern (often distinct brown stripes and tessellation in E. vidua), slightly produced anterior lip of aperture (rounded in E. vidua), brown columella and lip (brown columella, but white anterior and inner apertural lip in E. vidua);
There is also an ecological difference; in Hong Kong only E. radiata is found on the sheltered
shore of Tolo Harbour, whereas both occur on exposed coasts (Ohgaki 1985a). In this respect, and in its geographical distribution (e.g. on the Ryukyu Islands) E. vidua is a more oceanic species than E. radiata. This species occurs with others (E. melanacme, E. tricincta, E. reticulata) in Taiwan, and with E. melanacme in Vietnam, but confusion should not occur.

Japan, Korea, China, Vietnam. The species appears to occur all around the Yellow Sea. Ma (2004) records it from the entire Chinese coast and Song et al. (2000) from localities in South Korea. The species is rare at Nha Trang, Vietnam, and in the south of Taiwan. Unusually in the genus Echinolittorina, the distribution of E. radiata lies almost entirely outside tropical latitudes.
Habitat and ecology: Juveniles can be found among barnacles in the eulittoral zone, but adults extend upwards into the lower littoral fringe. Substrates include granite, basalt, slate, sandstone, limestone and concrete and the species occurs on both sheltered and exposed coastlines.