Found something weird

[Baron GAAL]

I found a corrupted sky island, made of ebonstone & demonite & more... in a crimson world :/
Look at the picture with the link:
https://ibb.co/cUdiYb

Is this normal ??

 

[Ivyss]

Are you using any mods?
If you are, it's probably from one.

 

[Th3KrustOfSk3l3tron]

that is why YOU are using mods (me too), because the Floating Island is a Demonite Island in Crimson worlds, with a corrupt chest from the dungeon

 

[Baron GAAL]

Yeah this might be one of my mods.
Thank you ^^

 

[Arlwiss]

It can happen when entering Hardmode. The game generates two diagonal strips, one of Hallow and another of the evil biome your world has, and these strips start at the center in the bottom of your world and go outwards. If there is a floating island in the path of a strip it will get converted as well.
Check the wiki for Hardmode for a proper explanation cause I think I may not have made it clear enough

 

[Kojiro_S]

That's from Calamity Mod. It will always create an island with the evil counterpart to that world on world-gen.