Gribbles bore into wood and plant material for food. The cellulose of wood is digested. The most destructive species are "Limnoria lignorum", "L. tripunctata" and "L. quadripunctata". According to an expert, they are the only animals able to make a cellulase to dissolve plant cell walls. Other animals that eat plant fibres make use of bacteria in their gut to produce the enzyme. Gribbles do not. This has led some biologists to think of biofuels.