Life under the sea can be nasty, brutish, and short if you don’t have an effective form of camouflage.

The cuttlefish’s skin, for instance, holds some ten million color cells, allowing it to impersonate a chunk of a coral, a clump of algae, or a patch of sand.

But for animals in the open ocean, there’s no place to hide. For them, the best camouflage color is no color at all—transparent bodies allow them to partially blend into their watery surroundings.

And now, a scientist has discovered that some of these animals possess yet another magician’s trick: antireflective coatings that render them nearly invisible.

“They are really hard to see when they’re in the water,” says Laura Bagge, a marine biologist and doctoral student at Duke University. “The only thing that gives them away is their eyes. The retina has to be pigmented. That’s the way it collects light.”