Glory Farm invites you to exchange and share about knowledge of Green sulfur photosynthetic bacteria which live together with Purple sulfur photosynthetic bacteria (or reddish brown colour). The green colour you have seen is not a kind of plant, e.g. moss, algae, etc., but it is green bacteria that using sulfur and sunlight in its process of photosynthesis. See a chemical formula of purple bacteria https://www.youtube.com/watch?v=ELyE8UtHskl in comparing with a chemical formula of green bacteria http://www.youtube.com/watch?v=Ue-hXmVnTkc&t=433s You can seen the usefulness of green and purple sulfur photosynthetic bacteria that provide to the plants in https://www.biotecharticles.com/Biology-Article/Green-and-Purple-Sulfur-Bacteria-705.html