they are layered mounds of deposits made by precambrian algae
Biosphere is one of the four sub systems of earth. It contains all the living things in the planet. So, plants and animals, as well as microorganisms are part of the biosphere. Humans can also be part of the biosphere according to some scientist, but others put them in another sphere - anthrosphere.
Answer:
Ocean-ocean convergences produce deep sea trenches.
Explanation:
