 The fruit body is 1 – 8 cm ( 0 @.@ 4 – 3 @.@ 1 in ) in diameter from tip to tip when expanded . The exoperidium is thick , and the rays are typically <unk> ( divided into small areas by cracks and crevices ) on the upper surface , and are dark grey to black . The spore case is <unk> ( lacking a stalk ) , light gray to tan color and 1 to 3 cm ( 0 @.@ 4 to 1 @.@ 2 in ) broad with a felt @-@ like or <unk> ( coated with loose scaly crust ) surface ; the top of the spore case is opened by an irregular slit , tear or pore . The interior of the spore case , the gleba , is white and solid when young , and divided into oval <unk> — a characteristic that helps to distinguish it from Geastrum . The gleba becomes brown and powdery as the specimen matures . Small dark <unk> threads ( rhizomorphs ) extend from the base of the fruit body into the substrate . The rhizomorphs are fragile , and often break off after maturity . 
