 Astraeus hygrometricus , commonly known as the hygroscopic earthstar , the barometer earthstar , or the false earthstar , is a species of fungus in the Diplocystaceae family . Young specimens resemble a puffball when young and unopened . In maturity , the mushroom displays the characteristic earthstar shape that is a result of the outer layer of fruit body tissue splitting open in a star @-@ like manner . The false earthstar is an ectomycorrhizal species that grows in association with various trees , especially in sandy soils . A. hygrometricus has a cosmopolitan distribution , and is common in temperate and tropical regions . Its common names refer to the fact that it is hygroscopic ( water @-@ absorbing ) , and can open up its rays to expose the spore sac in response to increased humidity , and close them up again in drier conditions . The rays have an irregularly cracked surface , while the spore case is pale brown and smooth with an irregular slit or tear at the top . The gleba is white initially , but turns brown and powdery when the spores mature . The spores are reddish @-@ brown , roughly spherical with minute warts , measuring 7 @.@ 5 – 11 micrometers in diameter . 
 Astraeus hygrometricus , commonly known as the hygroscopic earthstar , the barometer earthstar , or the false earthstar , <a href='drop_aux' title='1'><mark>is</mark></a>a species of fungus in the Diplocystaceae family . Young specimens resemble a puffball when young and unopened . In maturity , the mushroom <a href='uninflect' title='2'><mark>displays</mark></a> the characteristic earthstar shape <a href='null_relcl' title='3'><mark>that</mark></a><a href='drop_aux' title='4'><mark>is</mark></a>a result of the outer layer of fruit body tissue splitting open in a star @-@ like manner . The false earthstar <a href='drop_aux' title='5'><mark>is</mark></a>an ectomycorrhizal species <a href='null_relcl' title='6'><mark>that</mark></a><a href='uninflect' title='7'><mark>grows</mark></a> in association with various trees , especially in sandy soils . A. hygrometricus <a href='got' title='8'><mark>has</mark></a> a cosmopolitan distribution , and <a href='drop_aux' title='9'><mark>is</mark></a>common in temperate and tropical regions . Its common names refer to the fact that it <a href='drop_aux' title='10'><mark>is</mark></a>hygroscopic ( water @-@ absorbing ) , and can open up its rays to expose the spore sac in response to increased humidity , and close them up again in drier conditions . The rays <a href='got' title='11'><mark>have</mark></a> an irregularly cracked surface , while the spore case <a href='drop_aux' title='12'><mark>is</mark></a>pale brown and smooth with an irregular slit or tear at the top . The gleba <a href='drop_aux' title='13'><mark>is</mark></a>white initially , but <a href='uninflect' title='14'><mark>turns</mark></a> brown and powdery when the spores mature . The spores <a href='drop_aux' title='15'><mark>are</mark></a>reddish @-@ brown , roughly spherical with minute warts , measuring 7 @.@ 5 – 11 micrometers in diameter . 
Astraeus hygrometricus , commonly known as da hygroscopic earthstar , the barometer earthstar , or tdafalse earthstar , a species of fungus in thdaiplocystaceae fam . Young specimens resemble a puffball when young and unopened . In maturity , the mushroom display the characteristic earthstar shape a result of the outer layer of fruit body tissue splitting open in a star @-@ like manner . Thedalse earthstar an ectomycorrhizal species grow in association wid various trees , especially in sandy soils . A. hygrometricus got a cosmopolitan distribution , and common in temperate and tropical regions . Its common names refer to the dat that it hygroscopic ( water @-@ absorbing ) , and can open up its rays to expose the spore sac in response to increased humidity , and close em up again in drier conditions . The rda got an irregularly cracked surface , while the spore case pale brown and smooth with an irregular slit or tear at the toda The gleba white initially , but turn brown and powdery when the spores mature . The spores reddish @-@ brown , roughly spherical wwminute warts , measuring 7 @.@ 5 – 11 micrometers in diameter .