The honeycomb block can be found in Hives generated in the Nether, and can also be crafted with 4 empty honeycombs. When broken it drops 1-3 empty honeycombs. Axes break this block the quickest.
It can be used as a furnace fuel and smelts 1 1/2 items. It can also be placed as decoration.
All blocks found in hives aside from the honey block can be used as a furnace fuel.