Jeepers, Peepers! Tully Monster's Eyes Prove It's a Vertebrate

A tiny clue hidden in the bizarre eyes of the 300-million-year-old remains of a "Tully monster" has helped scientists determine that the curious creature is a vertebrate, a new study finds. Researchers analyzed the so-called monster's eyes, and found that they held two different kinds of pigment cells. Only vertebrates have these pigment cells that resemble sausages and meatballs, indicating that Tully (Tullimonstrum gregarium) wasn't an invertebrate, but rather had a backbone, they said.