The specific epithet, ndrosia, was derived from the native Fijian name for the species, ndrosi.

[1] Cassiopea ndrosia has eight oral arms, around 30 mm (1.2 in) in length, that have suction-mouths and leaf-shaped vesicles on their lower surface.

The upper portions of these arms can range from white to slightly gray; the suction-mouths are surrounded by small tentacles that are a deep brown color, and the vesicles are an olive-green.

The number of rhopalia can vary, with the original description noting there were instances of specimens having 18 and 22.

It has two sets of muscle bands; a number of these, in the lower bell, radiate towards the rhopalia.