The barreleye (Macropinna microstoma for you ichthyologists) is a deepwater fish that has a see-through, fluid filled head in which it moves its eyeballs. And that, dear reader, is freaking awesome.

Barreleyes, just a few inches long, are thought to eat small fishes and jellyfish. The green pigments in their eyes may filter out sunlight coming directly from the sea surface, helping the barreleye spot the bioluminescent glow of jellies or other animals directly overhead. When it spots prey (such as a drifting jelly), a barreleye rotates its eyes forward and swims upward, in feeding mode.