Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: Earthworms are deposit feeders. They burrow through the ground, eating soil and extracting organic matter from it. Earthworm feces, called worm casts, are very rich in plant nutrients. Earthworm burrows help aerate soil, which is also good for plants. Answer: deposit
Solution:
What type of feeders are earthworms?