Some scientists believe bryophytes called liverworts are some of the closest living relatives of early land plants; they are thought to have evolved from freshwater, multicellular, green algae. Fossils of liverwort plants were found in 2010 in the Central Andean Basin of northwest Argentina. The scientists who made the discovery believe that this bryophyte plant—which lacked stems or roots—may be evidence that plants evolved on land ten million years earlier than previously thought. They found spores from the liverwort fossil that dated from between 473 and 471 million years ago, making these very simple plants the oldest land plant remains found to date.