Trilobites strolled the seafloor about 380 million years ago. A thumb-size fossil that preserves the eye structure of one of these multilegged creatures indicates that at least some species were active during the daytime, a lifestyle that scientists previously had only suspected.
The newly unearthed example of Erbenochile erbeni is the first to include a head. This species had eyes like no other trilobite, says Richard Fortey of the Natural History Museum in London. Each of the spiny creature's two compound eyes was a semicircular tower that sported about 280 individual lenses. Together, the eyes took in light from all directions, even from directly behind the animal.