frozen egg under selchar

i found this weird frozen egg thing under selchar while doing the beneath the depths quest and i wanted to see if there was something behind a lava fall and i teleported into this room does anyone know what the frozen egg is for

 

Do you have a screenshot?

 

new mystery???
(if so this is the third egg)

 

Oh, that's a really, really REALLY old easter egg, it's pretty much an ancient build at this point. How did you manage to find it by accident?

At this point it doesn't really mean anything, I do recall another egg somewhere around the ocean with the same two enderdragon mobs spawning as enemies but I can't remember where exactly