A fungus with a double life. Young fruiting bodies, found in the spring, are flat, smooth, and an elegant gray, surrounded by a pure white margin. These are asexual forms and produce white, asexual spores. As they mature they expand and turn black or dark brown. They also become brittle and dry like charcoal. The mature form has many tiny black pimples which are the openings to the spore chambers (perithecia).

A parasite on many deciduous trees, including oaks, maples, and basswoods, all of which occur in the Park. Once the tree dies, the fungus continues to decay the wood.

The asexual, spring form is distinctive and unlikely to be confused with anything else. The mature form is scarcely distinguishable from the wood. It could be confused with common tarcrust (Diatrype stigma), but that forms a flattened layer on the wood.