Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: Some echinoderms can reproduce asexually by fission, but most echinoderms reproduce sexually. They generally have separate sexes and external fertilization. Eggs hatch into free-swimming larvae. The larvae undergo metamorphosis to change into the adult form. During metamorphosis, their bilateral symmetry changes to radial symmetry. Answer: sexually
Solution:
How do most echinoderms reproduce?