The Underworld: Journeys to the Depths of the Ocean

by Susan Casey

In the deep, there are creatures that breathe iron and creatures with glass skeletons and creatures that communicate through their skin. Some of its creatures can turn themselves inside out. They might have two mouths or three hearts or eight legs. Or their bodies might consist of a thousand little bodies, a coordinated army. At least one deep-sea creature squirts yellow light. Some have see-through heads. Even the most ethereal among them can handle pressures that would crush a Mack truck.

sixteen thousand pounds of pressure per square inch. (For reference, that’s 292 fully fueled 747s stacked on top of you.)