It would be GLUCOSE that is my best answer
Most cat litter is made from bentonite clay
Reef-building corals were
confined to relatively shallow depths because
many of these corals have microscopic algae
called zooxanthellae living inside their soft tissues.
These algae
are often important for the corals’ nutrition and
growth, but require sunlight for photosynthesis. There is no sunlight deep in the water.