Seaweed are not plants, but are algae. Not only do algae provide much of the Earth’s oxygen, they are also the base for almost all marine life.
It is estimated that marine plants produce between 70 and 80 percent of the oxygen in the atmosphere.
There are more than 7000 different species of algae. Most live in the oceans, but they also live in fresh water and even on land. Also, algae produce about 330 billion tons of oxygen each year.
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