DOD=ODD....................................[1..........................O]..........(i)
ONRUM=MOURN........................[1,2,&5......M,O,&N]..........(ii)
CROSITH=OSTRICH..................[1,2,&3.......O,S,&T].........(iii)
ERVNE=NEVER...........................[1,2...................N,E].........(iv)
From (i) to (iv)
O,M,O,N,O,S,T,N,E=MOONSTONE
Ans is MOONSTONE