Because some surface water might turn into ground water and some channels are there and it might go into a large body of water
Divergent evolution is when two different species share the same ancestral origins but have evolved differently whereas convergent evolution is when species with different ancestral origins have developed similar features.
In convergent evolution, two species that are not necessarily closely related develop similar features often as a result of adaptation to similar conditions.
Carbohydrate is the answer
The coral provides the algae with a protected safe environment (a home) and compounds they need for photosynthesis. The algae in return, produce oxygen and help the coral to remove wastes. Most importantly, zooxanthellae supply the coral with glucose, glycerol, and amino acids, which are the products of photosynthesis.
