Prototaxites, a mysterious genus of creatures that lived between 420 and 370 million years ago, grew large trunks up to 3 feet (1 meter) wide and 26 feet (8 meters) tall. Scientists debated whether these were strange ancient trees for a long time, but a 2007 study concluded that they were fungi, not plants. In 2007, study author and paleobotanist C. Kevin Boyce told New Scientist, "A 6-meter fungus would be odd enough in the modern world, but at least we are used to trees quite a bit bigger."