Saprophagy
Saprophages are organisms that obtain nutrients by consuming decomposing dead plant or animal biomass. They are distinguished from detritivores in that saprophages are sessile consumers while detritivores are mobile. Typical saprophagic animals include sedentary polychaetes such as amphitrites and other terebellids.
The eating of wood, whether live or dead, is known as xylophagy. The activity of animals feeding only on dead wood is called sapro-xylophagy and those animals, sapro-xylophagous.