It's undead.
It's dreaming. 1)2)
It's a catfish.
And somehow, it's the major divinity of some strange religion3) that nobody knows about.4)5)6)7)

1)
Or maybe, English being the nutty language it is, it's dreaming it's undead. Whoa. Concept. Like - it's not undead - it just thinks it is - whoa. Dude, that's - hey - do we have any Twinkies?
2)
By my reckoning, that'd be the “Undead-Dreaming Catfish God” (Note the hyphen).
3)
And/or cult
4)
Maybe it's the scientists that worship it.
5)
You never can tell with those guys.
6)
Maybe they just created it in one of their labs . . .
7)
Well, what are you just standing around for? Kill it!