It's not hard to know what's going on in the head of a Marcopinna microstoma fish…because you can see right through it! The fascinating creature is instantly recognizable thanks to the transparent and fluid-filled dome on its head, which also offers a glimpse of its eyes–and they aren't what you'd expect. You might think that they're the small, beady dots at the end of the fish's face, but those are actually its nostrils. The real eyes are the brownish tubes inside its head, punctuated by the bright green half spheres.

The six-inch-long M. microstoma lives far beneath the ocean at depths of 2,000 feet to 2,600 feet. It doesn't typically swim and instead hangs motionless in the water using its large, flat fins for stability. The fish points its eyes upwards to help sense the silhouettes of prey. When it finds something to eat (like a smaller fish or jellyfish), it shifts its body into a vertical position and rotates its eyes forward so that it won't lose sight of the meal.

First discovered in 1939, photographs of this peculiar fish weren't captured until 2004, which makes sense given the fact they live in depths of 2,000 to 2,600 feet! Better still, they tend to avoid swimming, usually preferring to float motionlessly in the water as they look for prey (typically smaller fish and jellyfish).

The discovery of the M. microstoma was first documented in 1939, but it was only in 2004 that it was photographed alive. Since then, researchers at the Monterey Bay Aquarium Research Institute have captured the fish in action. Scroll down to see the video, below. Above photo source: Imgur