Q: Given a scientific passage and an answer, generate a question for the given answer.
Passage: Mollusks are mainly aquatic invertebrates in Phylum Mollusca. They include snails, squids, and clams. Mollusks have a coelom and several organ systems. Most also have a shell, head, foot, and radula, which is a feeding organ. Mollusks are either free-living heterotrophs or parasites. Answer: mollusca
A:
What phylum includes snails, squids and clams?