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.