Q: Given a scientific passage and an answer, generate a question for the given answer.
Passage: The deeper water of a lake makes up the profundal zone. There isn't enough light for photosynthesis in this zone, so most organisms here eat dead organisms that drift down from the water above. Organisms in the profundal zone may include clams, snails, and some species of fish. Answer: dead organisms
A:
What do most organisms eat in the profundal zone of a lake?