These are used to burn the natural resins and botanicals.

One of the easiest ways of lighting the charcoal disk is using a candle and tongs. Hold the disk's bottom over the flame until it starts to crackle, then do the same to the top. Once alight, place the disc into a heat proof container, such as a metal censer.. The resin and dust melt and then burn, creating a smoke that is amazingly light and intoxicating.