Genea harknessii

Genea harknessii, commonly known as the dark geode truffle, is a species of fungus in the genus Genea. The species was described by Helen Gilkey in 1916. The mature fruit has a convoluted, brain-like appearance and often is no larger than an adult's thumbnail. The exterior is dark brown (to nearly black) with a hollow interior. The flesh between the dark interior and exterior 'skin' is white to pale grey.

G. harknessii grows underground in forests, especially white oak forests, but also in coniferous forests.