[dredmorbius]

This is where scavengers and decomposers come in.

It's relatively rare that living organisms die without being part of some further biological change, though that does happen. Fossil fuels are formed through lack of biological decomposition, as are precursor materials: peat bogs, kerogenated biomass, abiotic methane. Deaths in desert, arctic, or alpine conditions may simply dessicate and degrade rather than being eaten.

The entropic channel may pass through biological mechanism, but there's no obligation that it must.