Fire Coral
5-30 minutes after contact a stinging and burning sensation will be felt which may become very painful, red and swollen. Blisters and weeping lesions may develop. First Aid, wash with Sea Water (not fresh water, this will make it more painful) and soak with vinigar. If any pieces of coral get stuck or left in the wound, remove with tweezers. Watch out for allergic reactions or anaphylactic shock (not common tho)
and no need to worry about Sharks.... 'onest