Coloring by classification confidence. Human gut sample MH0072 from the MetaHIT project  was classified using PhymmBL and displayed using Krona. Abundance can be simultaneously visualized with an accessory attribute by linking it to hue. In this example, hue is used to display classification confidence as reported by PhymmBL. The average confidence value for each node is colored from low (red) to high (green), distinguishing uncertain from certain classifications. An interactive version of this chart is available on the Krona website.