After Vaan calmed down and rethought the matter on Deep-Sea Steel, he quickly realized it was possible for solid uranium to exist at the bottom of the sea.
It was general knowledge that the planet of Pangea was mostly covered in water.
However, the planet of Pangea wasn't necessarily a water planet at the very beginning of time. Water could have been something that came after, like how water came to Earth and brought life.
As such, it was quite possible that the surface of the planet was originally filled with uranium and the introduction of water that came after brought a cataclysmic change, transforming it into a toxic water planet.
However, such an event would have happened long before the Golden Dragon Pangea descended upon this world.
'Even if there used to be radioactive uranium at the bottom of the sea, it should be nonradioactive lead now. However, that also means there's possibly more uranium buried under this layer of lead,' Vaan mused.