http://www.sciencemag.org/news/2019/10/300-million-year-old-tully-monster-may-not-be-creature-scientists-thought-it-was

The mysterious “Tully Monster,” a 15-centimeter-long, stalk-eyed  creature (artist’s concept above) that swarmed the seas of what is now Illinois more than 300 million years ago, was a vertebrate and a close relative of lampreys. At least that’s what scientists concluded 3 years ago. An even more recent study seems to have confirmed that classification. But a new analysis could shake up this strange animal’s family tree.

This new effort focused on the eyes of Tullimonstrum, whose informal name honors the paleontologist who first discovered it. They homed in on melanosomes, microscopic, pigment-containing structures that often bind to metals such as zinc and copper, which possibly serve as antioxidants. Such structures were widely thought to be present only in the eyes of vertebrates, hence a previous team’s 2016 classification.