pipe: a long tube made of metal or plastic that is used to carry water or oil or gas etc.
tube: conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases
saxitoxin: a powerful neurotoxin produced by certain dinoflagellates found in red tides; it can accumulate in mollusks that feed on the dinoflagellates and cause food poisoning to humans