How many number of macro algal species available in the Earth?

There are approximately 20,000 to 30,000 species of macroalgae (seaweeds) documented on Earth. These can be broadly classified into three main groups: green algae (Chlorophyta), brown algae (Phaeophyceae), and red algae (Rhodophyta). The exact number may vary as new species are discovered and classifications are updated. Macroalgae play crucial roles in marine ecosystems and have significant economic importance.