99:4 Ashes from a stove that were burned before yom tov may be handled on yom tov because they are prepared for any need, such as to cover excrement or saliva. If these ashes were the result of burning on yom tov and they are still hot enough to roast an egg, they may be handled for any need. If they cooled off, they may not be handled because it is considered nolad (something that came into existence); yesterday it was wood and today it is ashes. Nolad is “worse” (i.e., more stringent) than muktzeh.
99:5 The shells of nuts that were eaten before yom tov may be used for fuel but not the shells of nuts that were eaten on yom tov; even handling them is not permitted. The same is true of other peels, even if they are fit for animals. They are considered nolad because yesterday they were suitable for people.