Wool
You can light steel wool simply by touching it with a basic 9V Battery. 🔥 However, unlike most items it will gain weight rapidly in the process. As steel wool burns, it draws oxygen out of the air to turn into iron oxide, commonly called rust. The extra weight of the oxygen atoms means steel wool gets heavier as it burns. https://twitter.com/HowThingsWork_/status/1719365157275447518