It is covered with a strong blackish cuticle, beneath which it is green.

The body whorl is large, flattened above, with incremental wrinkles and subobsolete spiral sulci.

The large aperture is oblique, rounded, pearly white within.

[2] Lunella smaragda is an endemic species found both at the intertidal and low subtidal rocky shores and soft substrates (including seaweeds) of New Zealand.

[3][4] It is found around the North, South, and Stewart islands, on rocks between low and mid tide.