When small, Lychnorhiza lucerna has a hemispherical bell, but this becomes flattened into a saucer shape as the jellyfish grows.

The stomach occupies most of the interior of the bell and there are a ring of small cream or white gonads round its edge.

The colouration of this jellyfish varies, but in general, the bell is translucent and colourless or a pale shade of buff, sometimes with irregular streaks of light brown.

The scyphistomae can strobilate several times and in a study it was estimated that one founder polyp could produce up to sixty ephyrae in a period of four months.

[3] Lychnorhiza lucerna has associations with the parasitic flatworm Dibothriorhynchus dinoi, shrimps Periclimenes spp, the Atlantic bumper fish, Chloroscombrus chrysurus and the bluntnose jack, Hemicaranx amblyrhynchus.