Huevo Frito
The Spanish call this jellyfish huevo frito, which means fried egg. Looking at this picture, it is easy to see why.
On the other hand, if this is an egg, it must have come from an ostrich, because it measures almost 12 inches (30cm) across.
For a closer look at part of this photo, follow the link.
For another photo of this same species, take a look at Brown Jellyfish.