seagrass

noun

1. (countable, uncountable)Any of various grass-like marine plants that grow underwater in salt water.

   “They are not seen again until they arrive as larger juveniles in shallow coastal waters, where they dine on seagrass and algae.”

   “There has been some investigation into the potential of seaweeds as a carbon store, and although more is needed, one study says that seaweed habitats are believed to be the most productive of all coastal vegetated ecosystems, and suggested that the world’s seaweed sequesters as much carbon as all the planet’s seagrass meadows, saltmarshes and mangroves combined.”