User blog comment:Sporekypig/Weird buildings theories?/@comment-2056021-20150405080632/@comment-1713205-20150809105707

The ruin in the ocean is in Grand Reef biome now, you can find them camouflaged with coral, same color as the ground.

For the island near Aurora, that one have been removed. Only some sand tips are sticking above the water surface now. I assuming you meant that island on the pic, and not actually the Floater Islands.