An Urn

And some people could not withstand the restriction of the Sea of Light which made them unable to fly. 

Not able to fly is not exactly a pleasant restriction if you have tasted the feeling of flying. But they are some people that did not mind losing the ability to fly

Today, when night descended, the Sea of Light like always glows with that ethereal light that seems to cover the world. 

Everything seems alright with the world.

But then the energy of the Essence of Death Monarch spread to the Sea of Light and something happened to the Sea of Light

 the Light that is always present in this expanse of the sea dimmed and the resident of the island near the center of the Sea of Light could see something.

Something that they could not have seen before because of the light that always fills the sea. But now that the Light dimmed, their eyes could see through it

Or maybe, it could only be seen when the light dissipated