Zostera marina
"Smaragdia viridis" is a marine littoral species. Minimum recorded depth is 0 m. Maximum recorded depth is 20 m. It is documented to feed directly on seagrasses, rather than on their algae epiphytes, as is the case with many other seagrass-associated snails. The species it feeds on are different in the two different areas of its distribution. In the Mediterranean the species has been recorded feeding on "Posidonia oceanica", "Zostera marina" and "Cymodocea nodosa" whereas in the Caribbean it consumes "Thalassia testudinum", "Halodule wrightii" and "Syringodium filiforme".