well, i was playing nillys realm like the nerd i am :3. and somebody told us to tp to an easter egg thing. i tped and found this at the right top corner there is a thing that says "easter egg" so... pretty obvious it is xd. Before this image there was a monster with 90k hp, it was like a lizard, and if it was close to the blood, it regened hp so fast, we killed it but dropped nothing. Was this already found? cause it looks cool
That monster is known as "Chaos", it's an unused monster in the game.
And parts like this are common to find in nr market/nexus/etc.