Astraeus hygrometricus Water MeasurerFruitbodies up to 5 cm across, with 6-15 acutely-pointed arms. Spore sacs hairy to felty, each with an irregular pore, exposed (inner) surface of arms ornamented with a network of fissures. Arms open when wet and close over the spore sac when dry and this response to water gives the fungus its common name. Widespread but not common; locally abundant in sandy areas. Not edible.