Back in 1986 a biologist named Cindy Lee Van Doverwas poking around the innards of shrimp from the bottom of the sea. They came from a hydrothermal vent in the Atlantic, where boiling, mineral-rich water came spewing up from cracks in the Earth’s crust and supported rich ecosystems of tube-worms, microbes, crabs, and other creatures. The animals that lived around these vents were generally blind, which wasn’t surprising considering that no sunlight could reach them. But Van Dover noticed that they had two flaps of tissue running along their backs that connected to nerves. Closer inspection revealed that the tissue was actually made of light-sensitive pigments and photoreceptors. What, Van Dover wondered, could these shrimp possibly be looking at.