Matthew and the bearded Goblin packed the materials into boxes, planning to make another copy once they transported them back.
Just when Matthew thought this room contained nothing but books, he suddenly noticed something unusual on one of the bookshelves.
As he took a book down from that shelf, he found a dried mushroom beneath it.
Its cap was made of deep red threads, resembling a jellyfish's tentacles, while its stem bore a series of regular patterns.
It was a Void Mushroom!
Matthew had seen Void Mushrooms in the Wizarding World. Their growth depended on Void Force, and they generally grew in the Endless Void. The Interstitial World, which was closely connected to the Wizarding World, was filled with Void Force, so seeing Void Mushrooms in the Wizarding World would not have surprised him.
But this was the Hogwarts World. Matthew had never seen a Void Mushroom here.
Although the Endless Void lay beyond every world, and Void Force could be found everywhere within it, an intact world possessed a World Barrier capable of completely isolating Void Force.
If Void Force appeared within an intact world, there were only two possibilities: either life in that world had mastered the ability to travel between worlds and could bring back things related to the void from beyond the world; or that world had been targeted by a Void Creature.
Matthew possessed the ability to travel between worlds, but he had never been here. This Void Mushroom could not have been left behind by him.
As for the other possibility... if a Void Creature had set its sights on this world... Matthew could not help but worry.
A Void Creature capable of breaking through a World Barrier was no ordinary opponent. It was not something he could handle.
There were also vast differences