Archaeologists have uncovered countless dinosaur bones, but what they have yet to find is a dinosaur brain — that is, until now. Researchers recently realized what they thought was a run-of-the-mill skull fossil actually may contain a chunk of fossilized dinosaur brain tissue. Scientists think the brain tissue came from a "large leaf-eating dinosaur, possibly from a species similar to the iguanodon," which roamed the earth some 130 million years ago, Mashable reported. The brain tissue, which looks like a nondescript brown rock at first glance, was found by an amateur fossil hunter in Sussex in 2004.