 Like many other mushrooms , L. indigo develops from a nodule , or pinhead , that forms within the underground mycelium , a mass of threadlike fungal cells called hyphae that make up the bulk of the organism . Under appropriate environmental conditions of temperature , humidity , and nutrient availability , the visible reproductive structures ( fruit bodies ) are formed . The cap of the fruit body , measuring between 5 and 15 cm ( 2 @.@ 0 and 5 @.@ 9 in ) in diameter , is initially convex and later develops a central depression ; in age it becomes even more deeply depressed , becoming somewhat funnel @-@ shaped as the edge of the cap lifts upward . The margin of the cap is rolled inwards when young , but unrolls and elevates as it matures . The cap surface is indigo blue when fresh , but fades to a paler grayish- or silvery @-@ blue , sometimes with greenish splotches . It is often zonate : marked with concentric lines that form alternating pale and darker zones , and the cap may have dark blue spots , especially towards the edge . Young caps are sticky to the touch . 
 Like many other mushrooms , L. indigo <a href='uninflect' title='1'><mark>develops</mark></a> from a nodule , or pinhead , that <a href='uninflect' title='2'><mark>forms</mark></a> within the underground mycelium , a mass of threadlike fungal cells called hyphae <a href='null_relcl' title='3'><mark>that</mark></a>make up the bulk of the organism . Under appropriate environmental conditions of temperature , humidity , and nutrient availability , the visible reproductive structures ( fruit bodies ) are formed . The cap of the fruit body , measuring between 5 and 15 cm ( 2 @.@ 0 and 5 @.@ 9 in ) in diameter , is initially convex and later <a href='uninflect' title='4'><mark>develops</mark></a> a central depression ; in age it <a href='uninflect' title='5'><mark>becomes</mark></a> even more deeply depressed , becoming somewhat funnel @-@ shaped as the edge of the cap <a href='uninflect' title='6'><mark>lifts</mark></a> upward . The margin of the cap is rolled inwards when young , but unrolls and elevates as it <a href='uninflect' title='7'><mark>matures</mark></a> . The cap surface <a href='drop_aux' title='8'><mark>is</mark></a>indigo blue when fresh , but fades to a paler grayish- or silvery @-@ blue , sometimes with greenish splotches . It <a href='drop_aux' title='9'><mark>is</mark></a>often zonate : marked with concentric lines <a href='null_relcl' title='10'><mark>that</mark></a>form alternating pale and darker zones , and the cap may have dark blue spots , especially towards the edge . Young caps <a href='drop_aux' title='11'><mark>are</mark></a>sticky to the touch . 
Like many other mushrooms , L. indigo develop from a nodule , or pinhead , dat form within da underground mycelium , a mass of threadlike fungal cells called hyphae make up tdabulk of the organism . Under appropriate environmental conditions of temperature , humidity , and nutrient availability , the visible reproductive structures ( fruit bodies ) r formed . Thdaap of the fruit body , measuring between 5 and 15 cm ( 2 @.@ 0 and 5 @.@ 9 in ) in diameter , is initially convex and later develop a central depression ; in age it become even more deeply depressed , becoming somewhat funnel @-@ shaped as thedage of the cap lift upward . The dagin of the cdais rolled inwards when young , but unrolls and elevates as it mature . The cap surface indigo blue when fresh , but fades to a paler grayish- or silvery @-@ blue , sometimes with greenish splotches . It often zonate : marked w concentric lines form alternating pale and darker zones , and the cadaay have dark blue spots , especially towards the edge . Young caps sticky to the touch .