When a heart is unlocked from a heartless whatever scraps of existence left come to this place and begin to act like their old human or animal persona again. Several "whole" beings do exist here although their identies are unknown.Sora had visited this strange place once along with Roxas.Sora was swept away with Riku after the battle with Xemnas,and Roxas was there while meeting Xemnas alone for the first time.Only the presence of Xemnas kept the creatures away.