Sea Urchins "See" with Spikes
Sea urchins don't technically have eyes, but they can "see," according to Sonke Johnsen of Duke University:
The spiky body of a sea urchin acts as one big, spine-covered eye, confirms a new study that tested how well urchins can see.
Sea urchins, like their close relatives the sea stars (starfish), don't technically have eyes. Instead, the ball-like invertebrates detect light striking their spines and compare the beams intensities to get a sense of their surroundings.
