Morays are eaten sometimes, but their flesh is often toxic and may cause sickness or death. To prevent contact and possible severe injury keep hands out of those rocky areas, holes and crevices. If you must, use a stick to probe. If you are fishing be careful, as dead fish, blood or bait will bring them out of their holes. They injure you with their razor sharp teeth and powerful jaws that can lock.
Injuries can result in bleeding, severe muscle damage - also chipped bones.
Stop any bleeding, clean wounds thoroughly. Get medical help to guard against infection.