▁Union ▁for ▁Conserv ation ▁of ▁Nature ▁has ▁r ated ▁its ▁conservation ▁status ▁as ▁being ▁" near ▁threatened ". ▁ ▁Description ▁Col on ies ▁of ▁this ▁cor al ▁form ▁massive ▁hem is pher ical ▁dom es , ▁stack s ▁or ▁pl ates ▁that ▁can ▁be ▁a ▁met re ▁( yard ) ▁or ▁more ▁across , ▁but ▁in ▁the ▁Red ▁Sea , ▁it ▁s eld om ▁exceed s ▁. ▁The ▁cor all ites ▁are ▁arranged ▁in ▁broad ▁me and ering ▁valle ys ▁with ▁ac ute - ed ged ▁rid ges ▁separ ating ▁them . ▁The ▁sept a ▁are ▁thin ▁and ▁even ly ▁spac ed , ▁and ▁slope ▁uniformly ▁to ▁the ▁central ▁col um ella . ▁The ▁poly ps ▁only ▁expand ▁at ▁night ; ▁they ▁are ▁large ▁and ▁f les hy ▁and ▁have ▁white - ti pped ▁tent acles . ▁The ▁colour ▁of ▁this ▁cor al ▁is ▁usually ▁some ▁sh ade ▁of ▁brown , ▁grey ▁or ▁green , ▁sometimes ▁with ▁contrast ing ▁or al ▁disc s . ▁This ▁cor al ▁is ▁somewhat ▁similar ▁in ▁appearance ▁to ▁Pl aty gy ra ▁da ed ale a . ▁ ▁Distribution ▁and ▁habitat ▁This ▁cor al ▁is ▁found ▁in ▁the ▁tropical ▁western ▁and ▁central ▁Ind o - P ac ific ▁region . ▁Its ▁range ▁extends ▁from ▁the ▁Red ▁Sea , ▁G ulf ▁of ▁A den ▁and ▁East ▁Africa ▁to ▁Australia , ▁Japan , ▁the ▁East ▁China ▁Sea ▁and ▁the ▁island ▁groups ▁of ▁the ▁West ▁Pacific ▁Ocean . ▁It ▁is ▁found ▁on ▁re ef s ▁at ▁depth s ▁down ▁to ▁about