The Neptune seagrass is a plant, not a seaweed, and like other plants it has roots, stem, leaves, flowers and fruits. The Neptune seagrass is an endemic plant of the Mediterranean Sea, adapted to living in a marine environment.
It forms large underwater meadows close to the beaches, from surface to 30 meters depth, and is considered a unique ecosystem for many species to hide, breed and feed, among them the endangered pen shell (Pinna nobilis). These ecosystems also reduce the erosion of the beaches.
The population of Neptune seagrass has declined all over the Mediterranean Sea due to coastal development, contamination, and mechanical damage from trawling and anchoring. It is a very low growing species, and takes a long time to grow back and re-colonize areas. The best time to observe it is in the summer, when the Neptune grass is at its maximum development, forming large and dense prairies, and in October, when this plant flowers.