If plant cells are autotrophs and animal cells are heterotrophs, what do you call organisms that get energy using processes other than photosynthesis and cellular respiration?

Surprisingly there is a third type.

Organisms have to make food by producing, consuming, and decomposing.

Producers are the organisms that make their own food from molecules and solar energy.

Consumers like us are the second type.

And the third type are decomposers, an organism such as a soil bacterium, fungus, or invertebrate (worms), that decomposes organic material.