Common names: Skull-shaped Puffball, Brain puffball.
Extract from Wikipedia article: Calvatia craniiformis, commonly known as the brain puffball or the skull-shaped puffball, is a species of puffball fungus in the family Agaricaceae. It is found in Asia, Australia, and North America, where it grows on the ground in open woods. Its name, derived from the same Latin root as cranium, alludes to its resemblance to an animal's brain. The skull-shaped fruit body is 8–20 cm (3–8 in) broad by 6–20 cm (2–8 in) tall and white to tan. Initially smooth, the skin (peridium) develops wrinkles and folds as it matures, cracking and flaking with age. The peridium eventually sloughs away, exposing a powdery yellow-brown to greenish-yellow spore mass (the gleba). The puffball is edible when the gleba is still white and firm, before it matures to become yellow-brown and powdery. Mature specimens have been used in the traditional or folk medicines of China, Japan, and the Ojibwe as a hemostatic or wound dressing agent. Several bioactive compounds have been isolated and identified from the brain puffball.