Was Akulahkan created from the remains of the original Numidium? If so, I guess the pieces are lost below Red Mountain. If not, then what happened to the original pieces of Numidium?

Numidium exploded becuase of the actions of the Underking, Zurin Arctus, somehwere in the Iliac Bay.

Akulakan was it's own beast, and should still be in the lava of Red Mountain.