A lot of time may have passed, but I just don't see anything backing up the idea that the entire floating continent can be found underneath the sea around the research centre. Nothing backs it up except the fact that they are positioned in approximately the same location on the world map, and as I said, more games than those two have something in the corner of the world map.

I know Bahamut is on the Floating Continent, but it should be noted that he lives on the top of a mountain, not at the bottom of some ruins. Actually, in FF3, Bahamut lays eggs, so I guess I should call him 'she', but anyway.

The glowing rocks and the crystals are not similar to eachother at all. There were 4 Crystals, all big and whole, not split up like in the ruins.