An apparatus in which a solid fuel mass is burned controls the burn rate to slow the burning process and extend the lifespan of the solid fuel mass. The apparatus has a base cup configured to receive a lower portion of the solid fuel mass, and a descent cup configured to receive an upper portion of the solid fuel mass, wherein the descent cup includes a flame orifice. The descent cup is telescopically associated with the base cup and moves toward the base cup as the solid fuel mass is burned, and a flame produced as the solid fuel mass is burned extends outwardly from the flame orifice of the descent cup.

A biomass burner includes a lateral shell having an axis of main development and a bottom provided in a lower end of the lateral shell to delimit the lateral shell at the lower part in order to internally define a compartment to contain the biomass. The bottom is able to support the biomass inside the containing compartment and is provided with one or more first holes configured for the introduction of primary air into the containing compartment.