A colour name straight from the palette of a Jack Vance novel.
Cinnabar, the mineral, is mercury sulfide, the source of vermilion.
Here the hue names the fungus, as it does the bark spice. This is the Cinnabar Polypore, 𝑃𝑦𝑐𝑛𝑜𝑝𝑜𝑟𝑢𝑠 𝑐𝑖𝑛𝑛𝑎𝑏𝑎𝑟𝑖𝑛𝑢𝑠, hosted on dead cherry, a small flare of colour where the work of decay is quietly underway.