Hotbed

In biology, a hotbed is a pile of decaying organic matter warmer than its surroundings due to the heat given off by the metabolism of the microorganisms in the decomposing pile.

A hotbed covered with a small glass cover (also called a hotbox) is used as a small version of a hothouse (heated greenhouse). The bed is often made of manure from animals such as horses that pass much undigested plant cellulose in their droppings. Thus hotboxes are to cold frames what hothouses are to greenhouses.

Some egg-laying animals make or use hotbeds to incubate their eggs: for example the brush turkey.