It's another world entirely, as difficult as it might be to believe. We're in something called a Fissure, which is distorted and unstable reality caused by out of control magic. People and objects slip through from other worlds.

[He pats the shark's head as it gives his arm a couple light tugs, then gives a tug of his own back.]

And the sharks are cute, though I wouldn't recommend doing this yourself unless you're immune to physical damage.