I Found A "ritual Stone" And I Have No Idea What It Is

So I was in the lower molten heights, not far from Maex... when this mob spawned. It looked like some sort of red imp or something and it had a ton of health, and it was probably pretty rare since I spent 5+ hours in its spawn location. When I killed it I got this...

Yes, my dumb self forgot to take a picture of the imp but this is real. At first I thought it was a part of the Doguns and Dwarves questline but I just finished that yesterday and I didn't have to use the stone once. I checked on Discord and the forums and I've never seen this mentioned. Has anyone here found this? Does anyone have any clue what it's for?

 

you remember the thingy u drop pigman meat in to open a door that leads into a cave with a chest? yea u throw that in it instead of pigman meat now

Edit: here it is

 

Thanks for the response!

(I was half-hoping it would be a part of some mysterious discovery though)