ember

An ember is a glowing piece left when a fire dies down. Red inside, grey outside, and still hot enough to relight.

The word is nearly always plural, and the embers of a fire are what you rake over before going to bed. Cooking over embers rather than flames is the whole principle of barbecue. The figurative use is about things almost gone, since the dying embers of a career or a season means the last of it. There is a warmer version too, since embers can be fanned back into flame.