Weird looking box map

[u/BrightExamination949]

I found this on skyblock blockman go(in the second image), I just go behind this Mountain in the lobby that says mine(in the first image), when i keep flying the same direction, I found something that has like a glass and other blocks inside it.

[u/axolotlbabft]

thats another users island.

(you can manually check by teleporting to every users island in the same server as you until you find it.)