Professional divers and dedicated explorers of oceans often relate stories of how they felt "something is watching" while they're in the deep.

Unseen eyes just out of the range of human vision, or camouflaged invisibly in the habitat, it's a reminder that we are the aliens in this amazing other-world.

And it also reminds us of the connections we share with all living beings. A certain kind of communication happens when eyes meet: even when one pair of eyes is behind a sheet of tempered glass and the other pair is gazing through unblinking orbs adapted for the inky depths.